I might be on the wrong track here, but in the 1861 census I have found a William Pinpraze age 40, copper miner, with a wife Jane age 35. No children. This William is born Illogan and Jane is b St Agnes. RG 9/ Piece 1582/ Folio 30/ Page 26
(there is a possible matching William in 1851 age 30 unmarr with parents Edward and Maria)
I note that Illogan and Camborne are only a couple of miles apart.
Perhaps this explains why William seems relatively old to have such young children.

In which case the 1861 marriage for William to Elizabeth Allen is more likely.
1861 census taken in April, Jane dies (?), William marries Elizabeth in Sept 1/4 1861?
It's possible.

More investigation required.