Bushby Relative or Frame Model?

After recently removing a Boulton family picture from its frame, I found the one of the elegant lady above hiding behind it.  Under the photo, hand written in pencil it says " 115 Gower Street W.  Brenda Johnson " The sticker on the back of the frame indicates it was made by Herbert Yates, a frame maker and gilder from 11 Petersham Road in Richmond and at Twickenham. Google Maps tells me this is in the southwest part of London a block from the Thames River and the current location of a Fish & Chips place.    

Elsie Bushby Boulton left her home in Milton, England in September of 1913 and I can only assume that she brought the frame with her.  The question I had was whether Brenda was a friend or relative or if she was a model whose picture came with the frame?  Was there even such a thing back then?

Today, 115 Gower Street is a University College of London student residence called Arthur Tattersall House.  This site gives some early history of the street and its buildings but no mention of its use in the 20th century.  

The 1901 Census of England has a 26 year old Brenda B. A. Johnson living at 108 Elgin Crescent, Kensington in London.  Her occupation is listed as a photographer.  Ten years later douments show Brenda still a photographer and not married, was living with her retired doctor father, at nearby 10 Chepstow Place, Bayswater, Notting Hill.    Her trail seems to run cold after that in London but perhaps she is the same Brenda Johnson who is noted on a ship passenger list heading to Victoria, B.C. on October 19, 1912.

Brenda Johnson was about 10 years older than Elsie and although both lived in England, I have not found any other connection between the women.  Being a photographer, perhaps she was recruited by Herbert Yates to be a picture frame model to help sell his wares?  If you know more about this mystery or have another guess, I'd love to hear from you!