Polly lived at Risby for many years - the address is actually a farm cottage.
Since Bertram didn't seem to have any farming background or connection to Suffolk I'm guessing here that Polly may already have been living at that address with Percy Symonds. She is shown at that address on Bertram's CWGC war grave entry - he having died 29/9/1918, home address being Ashdon, Essex. I don't think it necessarily means she was at the address in Risby on the day that he died, just that she was living there when the records were recorded after the war.
Percy James Symonds was actually born as James Percy Symonds in Essex and appears to have switched his names round as an adult. He was a groom - he enlisted in 1914 from home address of Ashdon, Essex - mother Emma next of kin - so one assumes after the war he found a job as a groom at Risby, Suffolk where he continued as a groom.
So, with the common theme of Ashdon between the 2 men (Bertrams home address when he died) and the home parish of Percy, seems logical to assume that after Bertrams death she and Percy got together and that when he got a job as a groom at Risby she went with him and that when Bertrams death entry on CWGC was recorded that is where she was then living.
We can only speculate on the circumstances. Polly and Percy didn't marry until 1921- presumably she would have had to find some means of support after Bertrams death and as Percy (whom she obviously got to know in Ashdon) was still single did she initially move with him to Risby purely as a housekeeper and things developed from there or were they already involved in a relationship?
Since we've no way of knowing the actual date CWGC added Bertrams entry to the list of war dead (1918 to 1920) we only know that at the time they did Polly was in Risby but had to be before 1921 as she was shown as P. Whistler and not under her subsequent married name.
The move to Risby appears to have occurred 1919 to 1920.
Annette