Although I consider that
If you do not have his b-cert, you'll need it in order to get back further.
If you do not have access to the 1841 census and are willing to take my word for it, the Bisley census at Shiverralls shows that George's father (or at least the person living with an Ann 30 [Wool picker] and family including a Harriett 8, Henry 6, Hannah 2, and Sarah 1) was named John Damsell aged 25 [waterman] all born in GLS. To be sure of such an assumption regarding G's father, I would obtain his b-cert.
A John Damsell's death was registered in the Reg. Dist. of Stroud in the Dec. qtr of 1844 (source - freebmd). The d-cert will tell you little more except the date, abode at death and name of the informant who might have been Ann.
Age 25 on the census means 25 to 29 inclusive so maybe John's baptism might be found in Bisley via the IGI - but do not rely on a submitted entry so go to
http://freepages.genealogy.rootsweb.com/~hughwallis/IGIBatchNumbers/CountryEngland.htm#PageTitleRegards again - I reckon that just about completes your request!
Chas