Thanks Brendan
I thought I had the answer to 21ac, but couldn't parse it.
I also had considered the answer to 15d, but couldn't see enough letters for the anagram, but it definitely means set.
Once you told me I was looking for a themed 28 in the wrong place, I found the right place and have nearly finished, just 26ac and 27d to do.
No rush today as no Montelbano. I don't fancy Billy Elliot again.
Yes Livia is a wet blanket.