Good find Mabel - I have been looking for that
Possible marriage
Grace THOMAS marriage Hugh WILLIAMS 16 May 1842 Llanbadrig
Both full age, both marked X
Hugh a bachelor, labourer, son of Hugh Williams a labourer
Grace a spinster, daughter of John Thomas a labourer
Possible birth
WILLIAMS, JOHN Mothers name - THOMAS
GRO Reference: 1845 S Quarter in OF THE ANGLESEY UNION Volume 27 Page 353
It is possible the John we are looking for didn't have birth registered.
I think his birth was more likely in late 1844, so no registration is possible.