I found this very tricky. I gave up trying to solve this unaided after an hour or more and spent the rest of the morning trawling Wikipedia. Got there in the end! Thank you Gozo.
The theme for today’s puzzle is artists, painters in particular. I knew maybe half of them, some were familiar names and the rest were just guesses.
| Across | ||
| 1 | BRAQUE | 
 Old tracks on canal bridge. Not half! (6) 
BR (British Rail, old tracks) on AQUEduct (canal bridge, not half)  | 
| 4 | LANDSEER | 
 Would he shout “Ahoy!”? (8) 
shouted by a sailor who sees land  | 
| 10 | CHAGALL | 
 Brief visit taking in crone (7) 
CALL (brief visit) containing HAG (crone)  | 
| 11 | SICKERT | 
 Not so well at end of Lent (7) 
SICKER (not so well) with lenT (end of)  | 
| 12 | LELY | 
 Loss leader fronting cathedral (4) 
Loss (leading letter of) in front of ELY (a cathedral)  | 
| 13 | TINTORETTO | 
 Dictator with corrupt rotten heart (10) 
TITO (dictator) containing (with…heart) ROTTEN* anagram=corrupt  | 
| 15 | RUBENS | 
 Sport, live, with partners (6) 
RU (Rugby Union, sport) BE (live) with NS (partners in bridge)  | 
| 16 | WATTEAU | 
 Cheery greeting heard (7) 
sound like “What Ho!” (cheery greeting)  | 
| 20 | VERMEER | 
 Always following most of the pests (7) 
E’ER (always) following most of VERMin (the pests)  | 
| 21 | ROTHKO | 
 Took right-hand turn (6) 
anagram (turn) of TOOK and R (right) H (hand)  | 
| 24 | ALMA-TADEMA | 
 Dancing girl thanks dizzy dame (4-6) 
ALMA (dancing girl) TA (thanks) DAME* anagram=dizzy  | 
| 26 | GOYA | 
 Heads of Gregorian Order, years ago (4) 
first (head) letters of Gregorian Order Long Ago  | 
| 28 | CIMABUE | 
 Rod admits “I’m Jack” (7) 
CUE (rod) contains (admits) I’M AB (able seaman, jack)  | 
| 29 | TENNIEL | 
 Number at line-out (7) 
TEN (number) at LINE* anagram=out  | 
| 30 | ROSSETTI | 
 Weird stories about giant’s end (8) 
STORIES* aangram=weird containing gianT (end letter of)  | 
| 31 | RIVERA | 
 Flower – anemone, for starters (6) 
RIVER (flower, something that flows) then Anemone (starting letter of)  | 
| Down | ||
| 1 | BUCKLERS | 
 Fern’s small shields (8) 
BUCKLER (type of fern) with S (small) – small shields worn on the arm  | 
| 2 | AVAILABLE | 
 Woman apt to switch starters on menu (9) 
AVA (a woman) LIABLE (apt) with first two letters (starters) switched round  | 
| 3 | UTAH | 
 Posh topper raised in state (4) 
U (posh) HAT (topper) reversed (raised)  | 
| 5 | ALSATIAN | 
 Dog the French sent up – one possessed by the devil (8) 
LA (the, French) reversed (sent up) then I (one) inside (possessed by) SATAN (the devil)  | 
| 6 | DECORATION | 
 Award for cracking code 8 (10) 
anagram (cracking) of CODE and RATION (8 down)  | 
| 7 | EVENT | 
 It happened during the 70s (5) 
found inside (during) the sEVENTies  | 
| 8 | RATION | 
 Harangue not initially helping (6) 
oRATION (harangue) missing initial letter  | 
| 9 | ALL IN | 
 Exhausted in the centre of European capital (3,2) 
found in the centre of tALLINn (capital of Estonia)  | 
| 14 | INIMITABLE | 
 One small car overturned on plateau. Remarkable! (10) 
I (one) MINI (small car) reversed (overturned) on TABLE (plateau)  | 
| 17 | APHRODITE | 
 Success securing stick held by monkey goddess (9) 
HIT (success) containing (securing) ROD (stick) all inside (held by) APE (monkey)  | 
| 18 | DEAD BEAT | 
 Cold and cheerless round 9 (4- 4) 
DEAD (cold and cheerless) BEAT (round, a frequently trodden path)  | 
| 19 | COP A PLEA | 
 New appeal lodged under small company? Could be (3,1,4) 
APPEAL* under CO (small company) – I can’t properly explain the definition other than it being related to legal procedings  | 
| 22 | LANCER | 
 Soldier’s singular dance (6) 
LANCERs (a dance) singular hence no S  | 
| 23 | SMUTS | 
 Black marks for South African statesman (5) 
double definition – Jan Christiaan Smuts  | 
| 25 | MUMPS | 
 Parent’s admitted positive disease (5) 
MUM’S (parent’s) containing (has admitted) P (positive)  | 
| 27 | ANTI | 
 One praying heartily for opponent (4) 
the heart of a praying mANTIs  | 
definitions are underlined

Thanks Gozo and PeeDee. A tough one with about half a dozen of the artists unknown to me, and I didn’t really understand COP A PLEA either. Small typo in 13A – it should be TINTORETTO
19d: I looked up. When one ‘cops a plea’, one pleads guilty to a lesser charge so as to avoid standing trial for a more serious charge.
Hi Rishi, indeed, but how would ‘copping a plea’ be a new appeal lodged under a small company?
Thanks PeeDee.
Another gem from the gem-meister. I got the artist theme from the laugh out loud clues like 4, 11 and 16 across. Made the rest of it a bit easier, helped by the fact that I actually knew all themed answers. A very wide range of styles represented.
Seeing it was a Gozo puzzle, and seeing the preamble, I relished getting down to it, and have rarely enjoyed anything more.
Re 19d. I see it as an anagram of (new) appeal and co, small company.
Disappointing – if I want a GK xword I will seek one out. Cryptics should be only allowed perhaps one proper noun. I despair!
I’m with Wagonman @6.
There were lots of artists whose names I had not heard of. I spent lots of effort with Professor Google and in books to find the answer to many of these clues.
Wagonman and AID
I do understand. As someone whose GK doesn’t include any pop music, sport or television, I tend to feel bereft when themed puzzles on these make their not infrequent appearances. I was just relieved to get something within my ken.
(Once I clicked the wrong button on The Times site, and did the TLS thinking it was the regular daily one. ‘Home turf at last’, I thought foolishly. I learnt my error when I went to the blog to see if anyone had complained about obscurity.)
I can’t help wondering whether this is a reprint of a crossword compiled in the 1950s when people still said “What Ho!”, things were ‘U’ and ‘Non U’, ‘helpings’ were small because of ‘rationing’, Tito ruled Yugoslavia, people were regularly ‘all in’ after a long session with their bridge partners and ‘copped a plea’ if caught cheating…..
Hi Malta. There are a lot of people in this country who were alive in the 1950s. Where are you going with this one?
Hi PeeDee,
According to the 2011 census, 71.7% of the UK population would not have been alive in the 1950s.
Malta’s comments about the “history” of this puzzle are way off beam. It was compiled three months ago. 1950s, eh? I hadn’t even discovered crosswords then, being only a nipper.
I was disappointed to read of Wagonman and AID’s dissatisfaction with this themed puzzle. Such puzzles are very much my trademark for the FT. By the way, there was no need whatsoever for trawling through websites to verify the sixteen artists. All of them are listed in Chambers Complete Crossword Lists — a source of inspiration for many of FT puzzles — and thus I deemed it fair to include all their names.
Thanks for the update Gozo.
Looking through Wikipedia to find out about the various artists was a very pleasurable experience. Perhaps ‘trawl’ gave the wrong impression. For me finding out new stuff is one of the pleasures of cryptic crosswords. I had a very enjoyable morning’s work!
Thanks Gozo and PeeDee
Got off to a flyer with a few of the artists that I knew and quite a few of the down clues as well and thought that it was going to be an uncharacteristic ‘easy one’ from Gozo. That’s just before I hit the wall … and resorted to the electronics to help out to get finished.
As it turned out, I ended up getting SMUTS wrong with Ian SMITH at 23d – guess that it was a little tenuous to have the black marks suggesting a blacksmith. It’s been a bad week, picking up errors in quite a few puzzles :(.
An enjoyable and educational puzzle which I just grazed on across the day on the Monday after. Liked the layered hidden answer at 7d. Ended up in the SE corner with the last few in ANTI, TENNIEL and the erroneous SMITH.