This was the Goodwood Frame factory in Hackney owned by Victor Toogood; Bert Whittaker was given Victor's name by Peter Moon who was either involved (or running?) Sterling Armaments at the time.
Victor had been making wooden stocks for Sterlings AR180's to give them a more "sporting" look and appeal for the Britishgun market.
Bert Whittaker originally wanted Mansonia a west African tropical hardwood for his "Special"; Victor suggested Afromosia (African teak) because of its cost and availability, looking at the Whittaker's I have owned over the years it was a good choice!
Foot note:
Bert was a pipe smoker with a habit of tapping out his pipe on the heel of his shoe; Victor had to remonstrate with Bert that was something you didn't do in a factory where the floor was covered in saw dust and wood shavings!
Edited to add,
I have Victor's templates for the stocks in my attic!