2 changes to make script work on Python3 & Windows
2 changes to make script work on Python3 & Windows

Python 3:
csv.reader object's Method name changed from 'next' to '__next__'

Windows (10):
Binary file open mode was not working. Removing it left blank lines between all content-filled lines. 
#https://stackoverflow.com/questions/3348460/csv-file-written-with-python-has-blank-lines-between-each-row
Explained the issue and solution.

    output_file = open('BNGandLatLon.csv', 'wb')
->
    output_file = open('BNGandLatLon.csv', 'w+', newline='')
fmalina/bng_latlon,fmalina/bng_latlon,fmalina/bng_latlon,fmalina/bng_latlon