Guardian 23915/Bunthorne – A tough final challenge

The last puzzle from one of the very best setters.

Across
1 ACHILLES TENDON – I saw “heel” and stupidly assumed it was there to lead you away from Achilles. Unless it was a double bluff…
9 (IR)R(IS)ORY – a new word to me (meaning the act of laughing at another) which I finally got after trying combinations of IR, IE and is with RORY.
10 DD in HAS (rev) + U – the first of two ascetics in the puzzle. U=upper class=refined.
12 CRECHE – CR = councillor and “eche” is a Shakespearean word for “augment”.
23 TERIYAKI – anag of “a tricky” + ie minus ic. Not the easiest word to clue I would imagine so I thought Bunthorne did well here.
24 E + SNAIL (rev) – very misleading surface. “Elia” was the pseudonym of Charles Lamb so his fans are “Elians”. Excellent clue I thought.
25 LAH-DI-DAH – another tough word to clue. HAD I + HAD(anag) + L (all rev). The definition being “affected”.
26,27 SIMEON STYLITES (anag) – the second ascetic in the puzzle; a Christian saint and pillar-dweller.
 
Down
1,15 ANIMAL CRACKERS (anag) – ref Marx brothers film.
6 ETAERIOS – “soir” is the French word for “evening” + EAT + E, all “up”. This was the last answer I got. Obscure word but straightforward wordplay so very fair.
7 DIDICOYS – a new word to me but got it through the wordplay fairly quickly.  
13 ADULT, RANT around E.
16 IMPERIUM (anag) – meaning “absolute sovereignty”.
19 TINDAL – can = “tin” + LAD (child) “raised”. A tindal is petty officer of lascars.
20 BARDOT (anag) – Marianne is, and has been since the Revolution, a national emblem of France, personifying Liberty and Reason. Models for Marianne are chosen (I’m not sure who does the choosing) and have included Catherine Denueve, Laetitia Casta and Brigitte Bardot.