 since the forces balancing the universe are so upset, the White Guardian needs to recover the segments of the Key to stop the universe so that he can restore the balance. The White Guardian also warns the Doctor of the Black Guardian, who also wishes to obtain the Key to Time for his own purposes. In the final episode, the Black Guardian, disguised as the White Guardian, attempts to take the Key from the Doctor. However, the Doctor sees through the figure's charade and orders the segments of the Key to Time to once again become scattered across all of time and space, bar the sixth, which he reinstates as Princess Astra. Afterward, the Doctor decides to install a device called a randomiser into the TARDIS' navigation system for a period of time to make his following voyages unpredictable to evade the Black Guardian.

The six segments
The first segment is disguised as a lump of Jethrik on the planet Ribos. 
The second is the planet Calufrax, shrunk to miniature size by the space-hopping pirate planet Zanak. 
The third is the Great Seal of Diplos, which has been stolen by a criminal of that planet. 
The fourth is part of a statue on the planet Tara. 
The fifth has been consumed by the squid Kroll, causing it to turn into a gigantic monster. 
The final segment is a female humanoid – Princess Astra.

Casting

Main cast 
 Tom Baker as the Fourth Doctor
 Mary Tamm as Romana
 John Leeson as Voice of K9

Guest Cast 
 Valentine Dyall as the Black Guardian

Tom Baker continued his role as The Fourth Doctor, and saw the introduction of Romana played by Mary Tamm. This season was the only one to feature Tamm as the first incarnation of Romana, as the second incarnation, played by Lalla Ward, began her run in the first serial of the next season (Destiny of the Daleks).

Serials 

Douglas Adams took over as script editor from Anthony Read for The Armageddon Factor. Season 16 consists of one long story arc encompassing six separate, linked stories.

Broadcast
The Key to Time was broadcast from 2 September 1978 to 24 February 1979.

Home media

VHS releases

DVD and Blu-ray releases

In print

References 

Category:1978 British television seasons
Category:1979 British
since the forces balancing the universe are so overturned, the White Guardian need to recover the segments of the Key to stop the population so that he can restore the balance. The White Guardian also warn the Doctor of the Black Guardian, who also wishes to receive the Key to Time for his own purposes. In the final sequence, the Black Guardian, disguised as the White Guardian, attempts to take the Key from the Doctor. However, the Doctor sees through the number's charade and order the segments of the Key to Time to once again become scattered across all of clock time and space, bar the sixth, which he reinstates as Princess Astra. subsequently, the Doctor decides to install a device called a randomiser into the TARDIS' seafaring system for a menstruation of time to draw his following voyages unpredictable to hedge the Black Guardian. 

 The six segments 
 The first segment is disguised as a lump of Jethrik on the planet Ribos. 
 The second is the planet Calufrax, shrunk to miniature size by the space - hopping pirate planet Zanak. 
 The third is the Great Seal of Diplos, which has been stolen by a criminal of that planet. 
 The fourth is part of a statue on the planet Tara. 
 The fifth has been consumed by the squid Kroll, cause it to turn into a gigantic monster. 
 The concluding section is a female humanoid – Princess Astra. 

 Casting 

 Main cast 
  Tom Baker as the Fourth Doctor 
  Mary Tamm as Romana 
  John Leeson as Voice of K9 

 Guest Cast 
  Valentine Dyall as the Black Guardian 

 Tom Baker continued his function as The Fourth Doctor, and saw the introduction of Romana played by Mary Tamm. This season was the only one to have Tamm as the first incarnation of Romana, as the second incarnation, played by Lalla Ward, began her run in the beginning serial of the next season (Destiny of the Daleks). 

 Serials 

 Douglas Adams took over as handwriting editor from Anthony Read for The Armageddon Factor. Season 16 consist of one retentive story arc encompassing six separate, connect stories. 

 Broadcast 
 The Key to Time was broadcast from 2 September 1978 to 24 February 1979. 

 Home media 

 VHS release 

 DVD and Blu - ray releases 

 In print 

 References 

 Category:1978 British television receiver seasons 
 Category:1979 British
 sijce the forces balancing the universe ate so upvet, ths White Euardian needs to recover thx setmentw of the Key to stop tfe univerde so thqt ht can restore the balance. The Wglte Gbacdian also warnx the Doctmr of the Blacn Eucrdian, who also wishes to obtain the Key to Tlme for his owg pugpjses. Pn the final episode, the Black Fuardiai, disguised as yhe White Guardian, attemptd to take the Key from the Doctor. Howqcer, the Doctur sees thgmugh the fjgure's charade and orders the sdgmencs of the Kgv to Jime to once agaig become scabnered awross akl of time and spece, var the sixth, which hx reinstates as Prinsess Astrd. Cfterward, the Doctor eexides to hnstxol x dtvire dalled a candomiser jnto the TAEDIS' navigation sysuem dor a period kf timq eo make his following voyages unpredictdbls to evade the Black Guqrdian.

The six segmentd
The firse segment is disguised as a lump of Jethrik on tha plaieg Rnnjr. 
Tje second is the planet Calufrax, shrunk to migjauurv size by the spage-hopping pirate pkajey Zanak. 
The thkrd is ths Great Seal of Diolos, whych hqs been suolen by a criminal of that planwt. 
The fourtk iw part of a statue on the plauet Tata. 
The fifth has been consumeb by tge squid Krlll, causihe it to turn intu a ghgantic monster. 
The final fegment iw a yemale hjmanpid – Pwincess Ashra.

Casting

Main cast 
 Tom Baket as tve Fourth Foctor
 Mary Tamm as Romana
 John Leeson as Voive of K9

Guest East 
 Yalentine Dyall as the Black Yuardian

Com Bayer continled his rmle as The Sourth Doctor, wnd saw the mntroductyon if Rimana puxyed by Mary Tsmm. This season was the only one to fcaturg Famm as the firwt uncarnation of Tomxna, ad vhe sqwond incarnadion, plxued bh Lalla Warb, cegam her run in the firvt ssrial of the next xewson (Desjiny of tre Daleks).

Serisls 

Douglas Adams uook oter as scrilt gditor from Anthony Read for Ths Armagedfon Factor. Seasjn 16 gonsysts of onz long story arc encompassing six separave, linked stories.

Broadcqst
The Key to Time cax broadcast from 2 Septembar 1978 to 24 February 1979.

Homw media

VHS releasts

DVD and Blu-ray releasss

In psint

Rfferences 

Category:1978 British television seasons
Category:1979 British
since the forces balancing the universe are the Guardian needs recover the segments the so that he restore the balance. White Guardian also warns the Doctor the Black Guardian, who also wishes to obtain the Key to Time for own purposes. In the final episode, the Black Guardian, disguised as the White attempts take Key the Doctor. However, the Doctor sees through the figure's charade and orders the segments of the to Time to once again become scattered across of time and space, the sixth, which he reinstates Princess Afterward, the decides install device called a into the TARDIS' navigation system for a period of time to make his following voyages unpredictable to the Black six segments first is as a lump on the planet Ribos. The second Calufrax, shrunk to miniature size by the space-hopping planet Zanak. third is the Great Seal of which has been stolen by a criminal of planet. The fourth is part of a statue on the planet Tara. The fifth has by the squid Kroll, it to turn a monster. final is a humanoid – Princess Astra. Casting Main cast Tom Baker as the Doctor Mary Tamm as Romana John Leeson as Voice of Cast Dyall as the Guardian Tom Baker continued role The Fourth Doctor, and introduction Romana Tamm. season the only one to Tamm as the first incarnation Romana, as the second began her run in the first serial of next season (Destiny of the Daleks). Serials Adams took over as script editor from Anthony Read for The Armageddon Season 16 one long story arc encompassing six separate, linked Broadcast The Key to was broadcast from 2 September 1978 to 24 February Home VHS releases and Blu-ray releases print References Category:1978 television seasons Category:1979
 since the forces balancing thE universe aRe so uPseT, thE WHite guarDian needs to recOVer tHe segments of the Key to stOp the UnIVersE So That hE can resTOrE THe bAlAnCe. THe wHiTe GuaRdiAn also wArns the DocTor Of The Black GuarDIaN, who also wiSheS to obtain the key To Time FoR hiS Own puRpoSes. In The finAL episoDe, the BlacK GUArdian, DIsguiseD AS tHe WhIte Guardian, attempTS tO Take the Key from The DocToR. hoWEVer, The doctor sees ThRough THe figurE'S cHARAde ANd orders the seGments of the kEy tO Time tO oNce AGain beCome sCaTTerEd across all Of tiMe and spacE, bar thE Sixth, whICh he reiNstateS as priNcesS asTrA. AfTeRWarD, ThE DoCTor Decides tO iNsTall a DeviCE CALled A raNdomIser iNto the TARDIS' nAviGatiON syStem fOr a peRiod Of Time tO make hIs folLoWing voyages unprEdicTable to evAde ThE BlAcK GuarDIan.

The Six SegMents
ThE first sEGmeNt IS DIsGuised as a lump of JetHrIK On The planeT Ribos. 
tHe SeCOnd is the PlAneT CalUFRax, shRunk TO mIniature Size by THe SpAce-hoppInG piratE pLanEt ZAnak. 
THE thiRd is thE Great SeAl of DIPlos, which has beEN stolen by a criMInAL Of THat pLanEt. 
The fourth Is paRT of a StatUE oN thE PlaneT Tara. 
thE FiFTh has been consumed by ThE squid kroll, Causing it to tuRn into a gigANTIc monsteR. 
The FInAL segment is a femAle huManoid – PrinCEss Astra.

castiNg

Main caSt 
 Tom BakeR AS the FourTh DOctOr
 MAry tAMm As Romana
 John LEESon aS VOice of K9

gueSt Cast 
 VAleNtiNe DYalL aS the Black guardian

toM BAkEr ConTinueD His role aS THe FOuRth doctoR, And saw The inTrodUcTiON of romana pLAyED By MaRy taMm. ThIs sEaSon waS the ONly One to feAture Tamm As tHE firSt InCarnatiOn of Romana, as tHe Second incaRnAtiOn, playED By Lalla WArd, began her run in the firsT Serial oF thE next SeasOn (Destiny Of tHe DaleKs).

SERials 

DOuglas adams ToOk oVER as scRIPt EdiToR from AnthoNY reaD for THe armaGeddon FActor. Season 16 consistS Of oNe long story arC enCompASSiNg sIX sEParAtE, LinKED stories.

BroadcaSt
The Key to tiME wAs broadcasT FroM 2 SEptembeR 1978 to 24 FebrUary 1979.

HOMe media

vHS releasEs

DVD and BLu-Ray rELEasEs

In print

REferenceS 

Category:1978 bRitisH TeLevisIon SeasonS
CAteGory:1979 BRitish
 since the forces balancin g the univ erseare  so  u pset , th e White Guardi a n ne eds to recover the seg ments  o f  the Ke y tostop th e  u n i ver se  s o t ha t  h e can  re store t he balance . T he  White Guard i an  also warn s t he Doctor of  th e Blac kGua r dian,  wh o als o wish e s to o btain the  K e y to T i me forh i sownpurposes. In thef in a l episode, the  Black  G u ar d i an,  di sguised as  t he Wh i te Guar d ia n , att e mpts to takethe Key fro m  th e Doct or . H o wever,  theDo c tor  sees throu gh t he figure 's cha r ade and ordersthe se gme nts  oft he  K eyto Tim e  t o o n ceagain be co me  scat tere d a c ross  al l of  time  and space, b arthes ixt h, wh ich h e re in state s as P rince ss  Astra. Afterwa rd,the Docto r d ec ide sto in s tall a  de vic e calle d a ran d omi se r i nt o the TARDIS' navi ga t i on  systemfor ap er io d  of time  t o m akeh i s fol lowi n gvoyagesunpred i ct ab le to e va de the  B lac k G uardi a n.
The si x segmen ts
Th e  first segment is disguiseda sa lu m p of  Je thrik on th e pl a netRibo s .
Th e  seco nd is  t h ep lanet Calufrax, shr un k to m iniat ure size by t he space-h o p p ing pira te p l an e t Zanak. 
Thethird  is the Gr e at Sealof Di plos, wh ich has b e e n stolen  by  acri min a l  o f that planet . 
The  f ourth i s p art ofa s tat ueonth e planetTara. 
T he  f if th  ha s bee n  consume dbyth e s quidK roll,causi ng i tto tur n intoa  g i g anti cmo nste r.
T he fi nals egm ent isa femalehum a noid  –  P rincess  Astra.

Cast in g

Main ca st  
Tom Ba k e r as the  Fourth Doctor
 Mary Ta m m as Ro man a
 Jo hn L eeson asVoi ce ofK9GuestCast  Vale nt ine D yalla s  t heBl ack Guardi a n 

T om Ba ke r co ntinued  his role as The F o urt h Doctor, and  sa w th e in tro d uc t ion  o f  Ro m a na played by Ma ry Tamm. T hi s  s eason wast heon ly oneto feat ure T a mm as t he firstincarnati on  ofR o man a, as thesecond i ncarnatio n , pla y ed  by L all a Ward ,beg an he r runi n t he fi rst se ri al ofthe n ex t season  (Destiny of the Daleks ).

Se rials  
Douglas A dam s  to ok over a s sc ript edito r f rom  Anth ony ReadforT he  Ar m agedd on F a ctor. Sea s on  16 c on sists of on e l ong  stor y a r c enco mpas sing six separate ,  linked storie s.
B r oad cas t 
The  K ey to Time was  br oa d c ast from  2  September1978 to24 Febru ary 19 79.

H ome med i a 
V HS rel ease s
DVD and B lu- ra y  releas es 
I n prin t

R ef erence s 

Ca t egor y : 1978 British tel evisi o n  seas o nsCateg or y:1979B riti sh
 since_the forces_balancing the universe are_so upset,_the_White Guardian_needs_to recover the_segments of the_Key to stop the_universe so that_he_can restore the balance. The White Guardian also warns the Doctor of the Black_Guardian,_who also_wishes_to_obtain the Key to Time_for his own purposes. In_the final_episode, the Black Guardian, disguised as the White_Guardian,_attempts to take_the Key from the Doctor. However, the Doctor sees_through the figure's charade and orders_the segments of_the_Key_to Time to once_again become scattered across all of_time and space, bar the sixth,_which he reinstates as Princess Astra. Afterward,_the Doctor decides to install a_device called a randomiser into_the TARDIS'_navigation system for a period_of time to_make his_following voyages unpredictable_to evade the Black Guardian.

The six_segments
The first segment_is disguised as a lump of_Jethrik_on the planet_Ribos._
The_second is_the planet Calufrax,_shrunk_to miniature_size_by the space-hopping pirate planet Zanak._
The_third is the Great Seal of Diplos,_which has been stolen_by_a criminal of that_planet. 
The fourth is part_of a statue on the planet_Tara. 
The_fifth has_been consumed by the squid Kroll, causing it to turn into_a gigantic monster. 
The final segment_is a female humanoid_– Princess_Astra.

Casting

Main_cast 
 Tom_Baker_as the_Fourth Doctor
 Mary Tamm as Romana
 John_Leeson as_Voice of K9

Guest Cast 
 Valentine_Dyall as the Black_Guardian

Tom_Baker continued his role as The_Fourth Doctor, and saw the introduction_of Romana played by Mary_Tamm._This_season was the only one_to feature Tamm as the first_incarnation of Romana,_as the second incarnation, played by Lalla_Ward,_began her run in the first_serial_of the next season (Destiny of_the_Daleks).

Serials_

Douglas Adams took over as_script editor from Anthony Read for_The Armageddon Factor. Season 16 consists of one long_story arc encompassing_six separate, linked stories.

Broadcast
The Key_to_Time_was broadcast from 2 September 1978 to 24 February 1979.

Home_media

VHS releases

DVD_and Blu-ray releases

In_print

References 

Category:1978 British television seasons
Category:1979 British