Fix the Specialist Sector factory
Fix the Specialist Sector factory

I believe topic_content_id in this context actually refers to the
content_id associated with this object, the specialist sector.

The naming is completely confused, which is probably how the topic
factory got dragged in here, where topic is also know as a policy
area.

alphagov/whitehall,alphagov/whitehall,alphagov/whitehall,alphagov/whitehall