Mrs Gertrude Roberts perhaps living at 7 Oakley Street, Chelsea (which keeps popping up) in 1902 to 1909 (Alice Benham had a practice at No 57). Also a Mrs Gertrude Roberts in 1920 was living at Aubrey Lodge, Aubrey House, Kensington, by Campden Hill Square. The House had an early history of suffrage activity, from the 1860s and in November 1933 the Lodge was advertised as being rentable as flats. During WW1 it was a hospital, probably closing in 1920. Mary Stocks retired there in 1915, so it has a good “pedigree”. 
Can you add more to our brief pen portrait of Gertrude and/or have ideas for other candidates for her seat at the table? Gertrude at Aubrey Lodge could well be the one, but our evidence is rather thin.
A Miss G. Roberts gave her address in the Women’s Who’s Who 1934-35 as the Child Welfare Centre at 87 Royal St, Lambeth. But she should be a Mrs?? And not necessarily a Gertrude. There are other Mrs Gertrude Roberts in the electoral registers in London in 1930s.
 Various references to the Lodge in The Times including: 3.7.1919 and 2.11.1933 and the 1920 PO Directory records Mrs Gertrude Roberts living at Aubrey Lodge.