Hi all. It has been nearly two and a half years since I last had the pleasure of blogging an Ifor puzzle (No. 1396: Up and Down and Round and Round) but this was worth the wait. It was right up (and down) my street. Thanks Ifor!
The preamble reads:
Across clues and entries are normal. Down clues (presented in column order for solvers’ convenience) are of two types. 12, one per column, are normal, but each answer must be replaced by a word thematically related to it as the entry. The other 12 must be considered as six pairs in presented clue order. Within each pair a single letter must either step up from the lower or step down from the higher before solving; there are three of each type. In order, the six letters spell out a surname. Solvers must highlight 22 cells showing his FLIGHT PLAN. Chambers Dictionary (2016) is recommended; 22 is in Collins.
Starting with the acrosses seemed like the sensible thing to do, but I made heavy weather of those. I had better luck in the downs, with some of the normal clues falling readily. It helped knowing that there was one normal clue per column, as the remaining pairs which would letter-swap could be more easily pinpointed.
The non-Chambers IATRICAL at 23a went in first and I also solved the (normal) clues for the crossing 19d and 24d early. Seeing that these down answers each had a right letter in the wrong place immediately made me think the entries would be anagrammed in some way. In fact, DACE and ARAK would be not merely anagrams, but also reversals. Aha! That fit perfectly with the preamble and title.
The surname which duly appeared, stepping up and stepping down from down clues, was:
ESCHER
It was pretty clear that there would be a depiction of the famous Escher staircase in the grid to find. I was in no hurry to end the fun, but the hunt would have been quicker had I remembered the name of the work, for it is there both in shape and title:

| Clue No |
ANSWER (ENTRY) |
Clue with definition underlined | ||
| Explanation, with quoted indicators in italics and ANSWER letters in bold caps | ||||
| Across | ||||
| 1a | DISSIDENTS | Refuseniks in society border imprisoned by forces (10) | ||
| S (society) and SIDE (border) inside (imprisoned by) DINTS (forces) | ||||
| 10a | ARIENS | They began in spring and could be turning nastier over time (6) | ||
| People born under Aries could be an anagram of (turning) NAS[t]IER without (over) T (time) | ||||
| 11a | DHURRA | Food crop in Germany that is universal, arriving from the East (6) | ||
| DH (in Germany that is, das heisst) + U (universal) + the reversal of (… from the east) ARR (arriving) | ||||
| 12a | KNEE SOCK | Regular rattle outside experience, reflecting pedal wear (8, two words) | ||
| KNOCK (regular rattle) around (outside) SEE (experience) reversed (reflecting) | ||||
| 13a | UNGLAD | Young ladies gathering, mightily displeased (6) | ||
| We have yoUNG LADies gathering the answer | ||||
| 17a | SO-HO | Long-distance call (across the Globe?) quiet when interrupted by first of two rings (4) | ||
| SH (quiet) is interrupted by O (the first of two rings); the second O follows. I liked across the Globe? – a novel indicator of a Shakespearean word! | ||||
| 18a | MNAS | Means to settle, spending Ezekiel’s capital? (4) | ||
| M[e]ANS is to be anagrammed (to settle) removing (spending) Ezekiel’s first letter (capital) | ||||
| 20a | SEA CAT | Shark dropping contents of meal being eaten (6, two words) | ||
| SCAT (dropping) with the inner letters (contents) of mEAl inserted (being eaten) | ||||
| 22a | IATRICAL | Satirical plays ignoring start of medical treatment (8) | ||
| Without its first letter (… ignoring start) sATIRICAL is anagrammed (plays) | ||||
| 27a | MERIDIAN | Freed institute constrained by purpose at highest point (8) | ||
| RID (freed) and I (institute) inside (constrained by) MEAN (purpose) | ||||
| 28a | PENMAN | Author in no place to conceal new name after comeback (6) | ||
| NP (no place) around (to conceal) an anagram of (new) NAME when reversed (after comeback) | ||||
| 29a | DODS | Democratic party backed as losing before polls (4) | ||
| D (Democratic) + DO (party) reversed (backed) + [a]S without (losing) A (ante, before) | ||||
| 31a | ANTE | Advance payment, about first half of entire rent (4) | ||
| A (about) + the first half of ENTire anagrammed (rent) | ||||
| 33a | KNEIPE | Innkeeper paid regularly to run this? (6) | ||
| Alternate letters of (… regularly) iNnKeEpEr PaId anagrammed (to run) | ||||
| 35a | ROSACEAE | Group of flowers grew around hole in one area (8) | ||
| ROSE (grew) around ACE (hole in one) and A (area) | ||||
| 38a | TIGRIS | Fool brought back gentleman over river (6) | ||
| GIT (fool) reversed (brought back) + SIR (gentleman) reversed (over) | ||||
| 39a | OGIVAL | Travel west via fixed latitude in the manner of a chart (6) | ||
| GO (travel) reversed (west) + VIA anagrammed (fixed) + L (latitude) | ||||
| 40a | SYNTAGMATA | Systematic groups chasing game, with many sat around outside (10) | ||
| TAG (chasing game) with MANY SAT anagrammed (around) enclosing it (outside) | ||||
| Down | ||||
| 1d | DATUM | Mad at umpire cr[e]ating just one item of information (5) | E | |
| MaD AT Umpire is containing (crating) the answer | ||||
| 25d | STRAPS SPARTS |
Leader of snare drums in bands (6) | ||
| The first letter (leader) of Snare + TRAPS (drums) | ||||
| 2d | NORI IRON |
What might be turning up on margins of Rumoi (4) | ||
| We are reversing (turning up) ON and adding the outer letters (margins) of RumoI | ||||
| 23d | ADENOID | Put together claims on<e> rising iodine in glandular tissue (7) | E | |
| ADD (put together) contains (claims) ONE reversed (rising) and I (iodine) | ||||
| 3d | NIS SIN |
Imaginary creature that’s kind of normal originally exists (3) | ||
| The first letter of (… originally) Normal + IS (exists) | ||||
| 19d | ATEN | Rever<s>ed divine taboo protecting god (4) | S | |
| Reversed, diviNE TAboo is around (protecting) the answer | ||||
| 4d | SLAES SEALS |
Dundee’s fruits are in sales, under length (5) | ||
| The A (are) in SALES is moved to the position after (under) L (length) | ||||
| 26d | SMEARY | Greasy mes[s] plastered over any antique (6) | S | |
| MES anagrammed (plastered) over ARY (any antique) | ||||
| 5d | INK | Links missing <c>over mark on paper (3) | C | |
| lINKs without exterior letters (missing cover) | ||||
| 14d | LAMINA ANIMAL |
One taken in by priest carrying name plate (6) | ||
| I (one) inside (taken in by) LAMA (priest) around (carrying) N (name) | ||||
| 15d | ECAD DACE |
Environmentally-responsive species deceased, losing even members undergoing mutation (4) | ||
| DeCeAsEd without the even-numbered letters (losing even members) anagrammed (undergoing mutation) | ||||
| 32d | REST | Soak, engulfing last of various li[c]e (4) | C | |
| RET (soak) around (engulfing) the last letter of variouS | ||||
| 6d | EDEN | Garden [h]edges of daphne lifted, being oddly pruned (4) | H | |
| The outer letters (edges) of DaphnE reversed (lifted) + bEiNg without odd letters (oddly pruned) | ||||
| 24d | KARA ARAK |
Bangle’s fate to lose money (4) | ||
| KAR[m]A (fate) without (to lose) M (money) | ||||
| 16d | NAILED DELIAN |
Lead in mobile held fast (6) | ||
| LEAD IN anagrammed (mobile) | ||||
| 36d | EGG | Part of clutch engaged, <h>armed without acting after leaving split end (3) | H | |
| E[n]G[a]G[ed] anagrammed (harmed) without A (acting) and also without (after leaving) – individual letters of (split) END | ||||
| 7d | TUSSAH | Fawn has do[e] upset, hiding head in shame (6) | E | |
| HAS and UT (do) reversed (upset) containing (hiding) the first letter of (head in) Shame | ||||
| 29d | MINED DENIM |
Tunnelled in earth in case of meteoroid (5) | ||
| IN and E (earth) in the exterior letters (case) of MeteoroiD | ||||
| 21d | CLIO | Cap<e> on information from Port Jackson about whales’ food (4) | E | |
| C (cape) + OIL (information from Port Jackson) reversed (about) | ||||
| 37d | AVO OVA |
Unconfined havoc in Asian capital (3) | ||
| Without outer letters (unconfined), hAVOc | ||||
| 8d | ARCHAEA | Class of micro-organisms in volcanic rock, <r>each evolving (7) | R | |
| In AA (volcanic rock), REACH is anagrammed (evolving) | ||||
| 34d | TARP PRAT |
Waterproof deck with onset of rain falling (4) | ||
| TRAP (deck) with the first letter of (onset of) Rain moving down (falling) | ||||
| 9d | ATOKAL LAKOTA |
Fatally losing pilot outside? All correct inside, with no issue at all (6) | ||
| fATALly without (losing) its exterior FLY (pilot outside), with OK (all correct) inside | ||||
| 30d | SELLA | Flog [r]are part of skull bone (5) | R | |
| SELL (flog) + A (are) | ||||
thanks for the helpful blog Kitty not to mention the wonderful puzzle Ifor. For me, IATRICAL went in last since I had IAMBICAL for the duration which almost works. I too thought (WLOG) that we were jumbling until I realized that these were indeed special-cases, aka reversals. Things went a lot faster from then on. German “that is” was a revelation!
Another first-class puzzle from Ifor. I knew the Escher work but not its title, which is why I didn’t realise that the replacements were reversals rather than anagrams until I was over halfway through. Excellent clues and an inspired implementation of the theme, as you’d expect from this top-notch setter.
A nice set of thematically relevant devices in the down clues and clever to find and fit in so many words which form real words on reversal. Fortunately, I spotted the reversal as the likely device quite early, but didn’t see its significance until I had a full grid and was able to get Escher. With some fairly challenging clues too, a fun and satisfying solve overall. Thanks Ifor and Kitty
Thanks all, and thank you also to Kitty for the comprehensive and accurate explanations. LC@1 – it’s hard to see how Chambers might justify its inclusion of dh, but there it is, and all is grist to the setter’s mill.
I’ve written a little about the background to the puzzle over at the Big Dave site.