Is there anyone out there that could help me please?

Am trying to find out where Grace Silverthorn was born. Think it was Trowbridge, Wiltshire, UK, but have been unable to trace her.

She married Henry Boucher, again, I think he was from Trowbridge area. Marriage took place in Bradford on Avon, Wiltshire on 9/11/1778.

Probably among other children, they had a daughter called Ann (Anne) Boucher, born around 1780s, probably in Trowbridge.

Ann married a John Blatch on 13/12/1798 in Trowbridge.

Can anyone help me please as I can find no further information on these people?

Thank you.
Tracey