Sorry for the delay - I had a veterinary emergency when I came home from work today. The cat had managed to develop an arterial thromboembolism (some sort of blood clot in the arteries), which can be fatal, so I had to rush her to the vets and she’s going to be in hospital for a while. I also forgot that my tea was in the oven when I noticed she was suffering, so came home to charred remains! Anyway, on to the crossword. This started out very easy in the brief glance I had time for this morning, and I finished off a third of it in two minutes. I was then in meetings for the rest of the day, and planned to finish it when I got home… Now I’ve finally got time to look at it, I seem to have developed “solver’s block”, but I’ll wade through and have a report up in the next hour or so.

Blimey, that was tough! A lot of obscure words, tricky definitions, one (22ac) I’d never heard of, but managed to guess and confirm on Wikipedia. I think the ones I got this morning were all the easy clues and none of the harder ones.

Across
8 S(HATTER)S - nice easy start…
9 U,TOP,IA=A1 rev
10 FRED=”thread” when pronounced by a Cockney - I needed the crossing letters to get this, and it was one of the last to go in.
11 MANCHE,STER(rest*) - La Manche is the French word for the English Channel. Exact translation is “the sleeve”.
12 S(OFF)IT - one of those words that builders and DIYers use, and I haven’t got a clue what they’re talking about! Got it from the wordplay, but had to look it up to check.
15 ASTILBE (its able)* - obvious anagram fodder, and I’d heard of the plant.
22 PAST,ON - never heard of them. A guess based on the wordplay and checked on Wikipedia, the Paston Letters seem to be quite important. Maybe I should visit the British Museum more often.
23 EVIL(live*),IN TENT - one of those phrases that you’ll never find in a dictionary. “which is antisocial” is a very loose and unsatisfactory definition, to my mind.
26 PEER,AGES - &lit with a sly dig at the government.
Down
1 C(HERO,OT(to rev))S - one of the last ones I got.
3 FER(M)AT - obvious from the “last theorem”, but took me far too long to spot that it was (after*) + M (last letter of “theorem”).
4 A,SIN,I,CO - Another guess from the wordplay, followed by a Google search to check. I found a great quote from Shakespeare’s Troilus and Cressida though: “Thou sodden-witted lord! thou hast no more brain than I have in mine elbows; an asinico may tutor thee.”
5 BUSH,BABY - primitive primate, that’s about right!
6 CINEMA - AMEN,I,C all rev.
13 FRI(TILL)ARY - I only knew it as a butterfly before, so this was another one I struggled with.
16 BROWN,IN,G - IN = “having assumed office”
19 RECEIPT - nice misleading cryptic def.
24 OPAL - See as in diocese, so it’s the ending of “episcopal”.

I always enjoy crosswords from Virgilius and this was no exception. I can’t see a theme which is unusual for Virgilius but maybe I haven’t looked long enough!