You would need to check the baptisms at Chilthorne Dormer to be sure. Could be that he was born at "Dormer" but baptised at Yeovilton because it was nearer to that church. (people walked a lot then!!)
1841 census age seems to be a bit out.If you information re pension and military service ties up with death cert, then the yeovilton baptism looks good.
Hope this helps.