Sorry, Debbi, I've only just picked up your reply (I've been a bit obsessed with another branch).
I'm afraid I don't know where William or Samuel were born. However, according to the IGI there was a christening of a William Towell in 1815 in St Mary Major, parents recorded as Samuel Towell and Sarah, so these seem a fair bet.
The only concrete information I have about Samuel is from William's marriage certificate - William's father was Samuel Towell and he was a plasterer (in 1842 he was, anyway). The information about William I have gleaned from various censuses in London - he was born in Exeter in 1815 or 1816. At the time of his marriage, he was a smith and later he was a sugar refiner.
Thank you.
Deborah
p.s. Are there any photos you would like from the Woolwich/Charlton area?