Hi Kim,
I looked at a transcript of St Leonard's, Welbury church records at the Records Office yesterday but could find no baptism for Thomas Wrightson, or any other Wrightsons. Searched from 1700 - 1755.
Re: the marriage for Thomas Wrightson:- Banns were read at Welbury on 23rd & 30th April and 6th May 1758, TW of this parish, Sarah Postgate of Stockton. There is no marriage in the Welbury register as far as I could see, just the Banns. On the Joiner Marriage Index there is 1 record of a marriage for Thomas Wrightson and Sarah Postgate in Co Durham in 1758 so I guess they married at Stockton?
Tilly.