One of the certificates I ordered arrived yesterday (hopefully that means more today!) - that for John Storey & Mary Forster's marriage. Looks like I was right about the possibility of Thomas's older sibs having a different mother, John is listed as a widower on this certificate. So once the other child's birth certificate arrives (today with any luck), I should have the first wife's name. And that might let me find John in 1851. The marriage certificate gives me father's names, but a cursory search for John with father William in 1851 turned up nothing. Even if the other certificates don't arrive today I should do some thorough searching for both John & Mary pre-1861 - although after that I suspect this may be the end of the trail for this family for now, as the Cumberland parish records aren't around online anywhere.
(And yes, zombies were shot in the evening, never fear! Rockband was played too, and myyy what a difference being sober makes ;) )