Hi Jeff,
it's a curious one isn't it - have saved a copy of 1861C, just trying to work out how I can share with you.
I haven't been able to trace Hannah either.
Currently I'm working on a theory that William's parents were John Lyndsell (b1795 Braintree/Sarah Ann Tyler b1792 poss Braintree). They have children from 1815-1827 but all the others are non-conformist. Can't work out why one would be different. However he is not William of Finchingfield 1821 or Great Canfield 1826, both have census appearances when William is in Braintree 1871C and it's clearly him on the census with wife no.2 from Ireland.
Sue