Good morning to you all,
In view of the fact that I haven't made a contribution in recent weeks, I thought that I would rectify matters yesterday and then found that no-one else had started the thread...
I found that this was relatively easy apart from 19d and I'd ended up with the right answer without knowing why. So [and I'll now confess my sins] I used another site to see whether anyone else had had the same problem and indeed they had.
To help you with the answer, you need to know that, in Cockney rhyming slang, China is an abbreviated form of China plate - mate. You now need to find a three-letter synonym for mate or friend and you'll be on your way!
With best wishes to you all and particularly to Old Gal and Pipesmoker, whose problems make mine pale into insignificance,
Caravaggio