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.