Wow, I hadn't thought about using WWI service records - learn something new every day - Thanks for that ShaunJ. I'll start doing a check on the names in the lists and see if anything or anyone familiar emerges.
I have already checked out the family in Rope Walk listed in the 1911 census, but no joy from that investigation, ciderdrinker.
rosie99, the informant on the death certificate was her sister, who was living in outer Surrey, with her husband and children throughout the war period and appeared to have no connection with Sunbury.
And, yes, Imber, I have read up on the background to 'Rope Walks', but there is no doubt that the location was Sunbury U. D. (Urban District) which, from 1894, comprised the town and parish of Sunbury-on-Thames until it was expanded in 1930.
Thanks everyone, JB.