Thanks Geting. I've been thinking I must be going crazy re 1a. Pretty slapdash of The Observer to publish it without checking.
Here's my contribution of a clue that would actually fit the grid:
Republican, Unionist politician is an arse
Love it phil10000 - made me laugh!
The anagram of 23a is a rather tortuous joining of disparate words and letters - I really only spotted it after I'd guessed the answer from the bowels of my memory.
Not finished yet - time now to press on with the day then come back to it later.
All finished but 19d unparsed. The def seems clear and I can get the last four letters from the second word in the clue but where do the first 3 letters come from?
I thought this was a bit trickier than usual but all good fun.