Nearest match I can find is:
RG10/2017/58/22
Thornford House, Thornford, Yetminster, Dorset
Gould, Hubert C Head M 39 Captain Militia. JP for Glamorgan b Trowbridge, Wiltshire
Gould, Isabel F Wife F 28 b Llanfrithtyd, Glamorganshire
Mainwaring, David Servant M 25 Butler b Aberdon, Glamorgan
I tried looking nationwide (well, OK, England & Wales!) for variations of Mainwaring.
There are 2 aged 22 (so born 1849), this one, another 2 aged 28 (b 1843).
All the others are 18 or younger, or 34 or older.
Your David could be overseas, or in Scotland?
Or there could be an awful transcription error!
