Hi, I finally has the chance to do some research on the company yesterday. It was called Favourite Toys Ltd and the George Road location was their production site, with head office in Hanover Street. In 1969 the site was called St James Works (this being the parish of St James in Holloway), and was numbered 5-11 Georges Road. The address was shared with Buffalo Products Ltd and Protectoplast Ltd.
It isn't entirely clear (and the present occupants have no idea!), but aerially it looks like the site was probably demolished and replaced by the existing buildings (the screenshots from the story don't seem to fit the geography there now!). The address is now called Georges Road Works and is occupied by Strummers Studios and Jazz Cycles. There is an MOT centre on one side, and St James School on the other (the white building with arches mentioned, has now been converted into flats).
The updated record on the location is here:
http://www.doctorwhol...ns/georgesroadno5to11