So, regarding the
wealth of William Douthwaite, I guess he could have inherited money from:
His sister Emma who died in 1916 spinster: £340
His mother Agnes who died in 1919 widow: £244 / 3 (brothers left) = £81
Total = £421 (or £19400 of today's money)
Plus IF his first wife Maggie Jane who died in 1945 left him: £1824 (£70300)
It all adds up to nearly £90000 plus what he earned himself.
I know all this is a lot of speculation

, but it fits with the idea that he had "a bit of money" when he married Mary Alice in 1947...