Just under half of this was a write-in and then it got really tough! I agree with comments about the dodgy definitions of 10a and 18d. I suppose 18d is referring to 'most large' in the sense of a large sum of money, but it's very tenuous, imo. It would have worked just as well with 'most neat' as the definition instead. Why be so obscure?!! 10a was an even worse offender, and it wasn't even a well constructed clue.
Although the answer was obvious from the clue, I also don't really get the definition of 26a. Why does the answer mean 'say'?
Thank you to Brenden for helping me make sense of 25a. And I agree with him that the word 'what' spoiled the surface of 17a, which was otherwise a great clue - so that's just a minor quibble.
Someone upthread was questioning the definition in 23a. I think it's because it's something you might wear on your thumb when performing a certain activity (more commonly, but not exclusively, performed by women) It still doesn't really work as a clue for me though.
Despite the quibbles though, there was lots to enjoy. I think (and I never thought I'd ever say this) that the spoonerism was my COD!
Thanks Everyman.