Phi, the setter with the most Inquisitors to their name, and only three others also have over 50: the late Schadenfreude, Kruger and Ifor.
Preamble: The 24 Calendar answers, whose numbers do not relate to grid entries, are clued in a significant order, and must be fitted in where they will go, subject to a specific constraint. This will reveal a message to be highlighted. Remaining clues are entered normally.
First, I noticed that the Calendar entries were in the even-numbered rows and the even-numbered columns – leave those for later and crack on with normal ones.
I to-&-fro’d between the Across clues and the Down ones, working my way at a moderate pace through the grid. I’d started late on Monday evening and with 3 of each still unsolved I called it a day. 
When I went back to the puzzle on Tuesday and had another look at those 6 unsolved regulars, they were soon whittled down to 2, those being 5d and 18d, both with only one letter checked from the crossing normal entries. Time to make a start on the Calendar …
I passed over #1, but #2 & #3 were easy given the cross-checking letters: ÉPERDU & WELT. Hang on a minute – in column 4 there was P__DU & in column 6 I had _LT, the terminal letters of those answers; I could simply enter the answers with their leading letters outside of the grid – not so much a case of thinking outside the box but rather writing there. And so in a merry procession I made my way clockwise around the perimeter, skipping over the odd one here & there and coming back to them later. In passing, 18d was resolved as EXTORT and 5d as WHERRET (Herr = old German guy? Hmm).
At one point I thought that the Calendar entries that ended on the right might be entered reversed, and the same for those that ended on the bottom – that way, it would always be the leading letters that had to be moved out – but I was soon disabused of that notion. It was a very impressive grid, but for me it was all over too quickly to be highly enjoyable. {I have a couple of little niggles with the wordplay for Calendar 7 and Calendar 22 noted in the table below.}
Thanks, Phi … and a Happy New Year (when it arrives).
(See also Listener #3844 by Charybdis.)
| No. | Clue | Answer | Wordplay |
| Calendar | |||
| 1 | Engineer holding rope twisted around vessel for liquid (2 words) | WATER POT | WATT (engineer) around [ROPE]* |
| 2 | Distracted by Debussy, always accepting piano of the French | ÉPERDU | E’ER (always) around P(iano) DU (of the, Fr) |
| 3 | Dry? Not dry, with litre put in | WELT | WET (not dry) around L(itre) |
| 4 | Our Prince (but not King) dancing naked? Not so (2 words) | IN CUERPO | [OUR PRINCE ¬ R (king)]* |
| 5 | Trim Scots and Welsh avoiding climbing uplands | SNOD | DOWNS< (uplands) ¬ W(elsh) |
| 6 | Conflicting current? Toilet aboard ship reduced worry (2 words) | HEAD SEA | HEADS (ship’s toilet) EA(t) (worry) |
| 7 | Old uproar about people of fashion and unusual American verse | OCTONARY | O(ld) CRY (uproar) around TON (people of fashion) A(merican) {it seems to me that “American” should come before “unusual”, not after} |
| 8 | Romanian composer subsequently seen working with company | ENESCO | [SEEN]* CO(mpany) |
| 9 | Monarch attending University is Fijian leader | RATU | R (Queen or King, monarch) AT (attending) U(niversity) |
| 10 | Targeted American about to back universities etc | ACADEMIA | AIMED (targeted) A(merican) CA (circa, about) all< |
| 11 | Civilisation maintained by Angela Merkel | ELAM | (Ang)ELA M(erkel) |
| 12 | Argument linked to support stocking | SPATTEE | SPAT (argument) TEE (support) |
| 13 | Rival smelted our metal | EMULATOR | [OUR METAL]* |
| 14 | Church getting publicity about large bakery item | ÉCLAIR | EC (church) AIR (publicity) around L(arge) |
| 15 | What a surprise is on a birthday, ultimately (2 words) | I SAY | IS A (birthda)Y |
| 16 | An option’s final component taken first, with no reflection | ANECHOIC | AN CHOICE (option) with last letter first |
| 17 | Long-dead body? A lot of illumination for Rebus | LICH | LICH(t) (light, Scots) |
| 18 | American naval expert eliminating last area linked to river creature in Arctic (2 words) | SEA BEAR | SEABE(e) (American naval expert) A(rea) R(iver) |
| 19 | Peace offering – new minted coin – after anger | IRENICON | N(ew) [COIN]* after IRE (anger) |
| 20 | County employees in groups | STAFFS | double definition |
| 21 | Exam time fixed after reflection | TEST | T(ime) SET (fixed) all< |
| 22 | Low frequency returns with low flying from grouse | MOORFOWL | MOO (low) FR< (frequency) [LOW]* {note that Chambers has F for “frequency” whereas FR is for “frequently”} |
| 23 | Up North, current broadcast is unfinished | AIRE | AIRE(d) (broadcast) {ref.: River Aire, Yorkshire} |
| 24 | Poet to brood successfully | SITWELL | SIT (brood) WELL (successfully) |
| Across | |||
| 1 | News agency with power to block story in Johannesburg rag (6) | LAPPIE | AP (news agency) P(ower) in LIE (story) |
| 3 | Individual penning note in religious books available at various prices? (6) | NON-NET | ONE (individual) around N(ote) in NT (religious books) |
| 7 | Sounded like a barrage? They initially clustered together, hiding source of light (7) | THUDDED | T(hey) HUDDLED (clustered together) ¬ L(ight) |
| 8 | Daughter’s attention greatly valued (4) | DEAR | D(aughter) EAR (attention) |
| 11 | Blend of whiskey, pure and straight (8) | UNWARPED | [W(hiskey) PURE AND]* |
| 14 | Spread fails to include right meat dish? (4) | STEW | STREW (spread) ¬ R(ight) |
| 16 | Actor in Armageddon? Millions enthralled (5) | MAGOG | M(illions) AGOG (enthralled) |
| 17 | Coral feature – assistance after centre falls out (4) | REEF | RE(li)EF (assistance) |
| 20 | After second question, pop star’s heading off cleaner (8) | SQUEEGEE | S(econd) QU(estion) (B)EEGEE (pop star) |
| 21 | Rudimentary material about a mathematical chart (4) | ABAC | ABC (rudimentary material) around A |
| 22 | Lazy person backed call to attend ballet centre? (7) | BOLSHOI | SLOB< (lazy person) HOI (call to attend) |
| 23 | Exercise system cheers first person in Germany, then Italy (6, 2 words) | T’AI CHI | TA (cheers) ICH (I, Ger) I(taly) |
| 24 | Developer in the thick of opening libraries for starters (6) | AMIDOL | AMID (in the thick of) O(pening) L(ibraries) |
| Down | |||
| 1 | Desire offer, after investing in upturn in fuel (6) | LIBIDO | BID (offer) in OIL< (fuel) |
| 2 | Second hour to see gazelle (4) | MOHR | MO (second) HR (hour) |
| 4 | Constant in display of colour applied to tense woollen fabric (6) | TRICOT | C(onstant) in RIOT (display of colour) after T(ense) |
| 5 | Blow for old German guy in damp weather (7) | WHERRET | HERR (Mister, Ger) in WET (damp weather) |
| 6 | Doctor’s probing of veins exhibiting poison (8) | VENOMOUS | MO (doctor) in VENOUS (of veins) |
| 9 | Repeated each line about farm animal living close to the ground (8) | EPIGAEAL | 2×EA(ch) L(ine) around PIG (farm animal) |
| 10 | Close to start of January, river’s disappeared (4) | NEAR | NEW YEAR (start of January) ¬ WYE (river) |
| 12 | A bird, soaring, having disposed of last seaweed (5) | ALGAE | A EAGL(e)< (bird) |
| 13 | Muse, and, putting Spain over France, choose again (7) | RE-ELECT | REFLECT (muse) with E (Spain) for F (France) |
| 15 | Weak solution following charitable donation (4) | WAQF | W(eak) AQ (solution) F(ollowing) |
| 18 | Milk and rusks primarily consumed by former child? (6) | EXTORT | R(usks) in EX- (former) TOT (child) |
| 19 | Drab colour is replacing first line on ticket (6) | ISABEL | LABEL (ticket) with IS for first L(ine) |
| 21 | Remarkable person working in A&E (4, 2 words) | A ONE | ON (working) in AE |
Enjoyed: all thanks (and festive greetings) to Phi and HolyGhost. I am not one to complain about a relatively gentle challenge, though in fact the “outside the box” aspect was slow to dawn on me despite its having been done in past puzzles.
A daunting preamble from Phi. I thought it wise to start on the normal clues and soon found I had done about three-quarters of them, giving a good skeleton for starting the 24. I solved three in the SE corner which gave me the un-entered letters ER-Y. Bearing in mind the implied theme, I thought MERRY? Then a quick letter count led to the likely (and correct) message. In a flash, the Calender clues became hugely more approachable. I now knew the the location, length and leading/trailing letter of each entry. Again, all the clues were pretty fair, although I did need Chambers and Bradford to confirm some unfamiliar words.
So, a surprisingly easy IQ from Phi, probably the easiest I can recall. But, nevertheless enjoyable.
Thanks to him and to HG. I echo the message to them both and all other 225ers.
A very enjoyable solve! We were very thankful that things fell into place as we were busy sorting out things for an up and coming trip.
It took us a while to figure out that the letters were positioned ‘outside the box’ – a very neat construction.
Thanks to Phi and HG. We’d also like to echo the message to John and all the other IQ addicts.
Lest Phi make his future Inquisitors harder again, I actually thought this was tricky enough! It took me quite some time to figure out the Advent pattern, even though I had spotted ISTMAS as the first letters of the last 6 Advent clues quite early on.
On a minor note, I agree with HG on the placement of “unusual” in 7-ADV and had actually wondered why it was there at all, given the clue works perfectly well without it. I was not aware that “Fr” is not a Chambers-approved abbreviation for Frequency, but additionally question the word “from” in 22-ADV, which seems superfluous and once again the clue would work fine without.
On the other hand, 5d seems fine to me given that “old” refers to the blow not the German guy (as you seem to indicate in the preamble).
Overall a lovely puzzle and a quite novel device of the overhanging letters – how convenient that the message had exactly 24 letters!
Thank you to Phi, HG and everyone else involved in producing and blogging Inquisitors! (Though it feels a bit early to say “Merry Christmas” somehow.)
I also found this tricky enough, with very little progress on the Calendar clues (though enough to notice an anomaly), until I solved ‘Staffs’ and saw where it should go, and how. A quick count of the remaining calendar clues after Staffs, and the remaining possible entries north of Staffs, gave the game away and it was more or less a breeze from then on. Many thanks, and happy Christmas, to Phi and HG, and all.