The owner of the photo's grandfather (marked in red) is the only person we can definitely name. His name was Wilfrid Gregory, he worked for BMR/BDR for a considerable time and he can be seen again in the second photo taken around 1942 while the company was engaged in making tanks in Swineford near Bath.
Mr Gregory's grandson tells me his grandfather was very proud of the work he did designing and making the new London underground ticket machines the company became famous for.
He would be very grateful in anyone can put names to anyone else in the photo. I'm assuming the seated man in the front was one of the owners... but which one? Clearly the staff are in fancy dress but who were the men dotted among the crowd and flanking the front row all wearing the same odd uniform? A blow up of the photo shows their cap badge and jacket badge to be very like the company badge used later in the companies life (photo 3).
A long shot but info much appreciated.