In 1851, Job and Mary are in Bronygarth (Parish of St Martins, Shropshire). Again, this is one of those 'edge' townships on the very border with Llangollen and Chirk parishes.
At this time, Job was a Sawyer, but it is definitely them - he born Llangollen, circa 1813 and Mary, b. Llanymynech. They have their one year old daughter, Mary, with them. This would suggest a marriage between 1848-1850, probaly Oswestry Registration District.
You haven't mentioned the 1842 marriage before. It's possible but iffy

Alternatively, it might be worth trying to find the birth registration of Mary (between April 1849-Mar 1850) or one of the other children. This will give mother's maiden name.
Gadget