This was a very old post and you may well have got your answers by now, but in case you haven't, I think Herbert William's wife was actually Annie Ellen Dowsing - possibly known as Ellen. Annie E Sennett died aged 65 Battersea Dec Q 1941. This is the only one I can find from 1930 to 1947, but her age isn't quite right for having been born 1871/2 (from 1901 and 1911 censuses). I did wonder if she might have remarried, but couldn't find that either. Are you sure that E Sennitt was the wife? If that was the informant, then it could be Edward, the son, in which case Annie Ellen may have even died before Herbert.
I have four, possibly five children for them.
Alice Beatrice b 1897, Barnet, middlesex
Herbert William M b 1900 Camberwell
Maude Ethel b 1902 Chelsea
Edward George b 1908 West Ham, Essex
There may be a fifth - Joan or Anne, but I didn't record where I got that one from and she isn't on census 1911
pm me if you want more info.