PINK – what other combo would we expect for a centenary puzzle?
Preamble: Clues are in normal order. Solvers must temporarily insert the same letter into each of the barred-off cells such that it could be plugged correctly into the circumscribing 8-letter words; a phrase describing the outcome (6, 9) must be written under the grid. Each group of nine cells must then be emptied and further bars added to show relevant symbols as exemplified by the puzzle’s title; no other bars are to be shown. At all stages the grid displays 180° rotational symmetry and contains real words.
This was, as one might expect, slow going. After quite some time with nothing yet written in the grid, I realised that the second & fourth across answers (SOME & ÉTAPES) were not towards the right of the first two rows, but were in fact on the left of rows 2 & 3, to mesh with HOT-AIR (the first down answer), confirmation coming from IMAUM & PIET (columns 3 & 5) plus VAULT (row 4). At last I could extract WHIPPOORWILLS across the top, fill in fragments of the lower half – locations inferred from symmetry – and solve MULTINUCLEATE across the bottom. I was on my way. Time to call it a day.
After some more plodding, and progressively less cold-solving, I had the grid more or less complete (that is, encouragingly few empty cells). 
It wasn’t too difficult to pick out the circumscribing 8-letter words – INSULTED – and then temporarily insert an A into the barred off cells to give INSULATED. Rather than moving straight onto “the phrase”, I finished off the rather troublesome central section of the grid, completing it with YODLE, then took a break.
“The phrase” was eluding me, so I searched for a pattern match of “?????? INSULATED” and nanoseconds later, there it was: DOUBLE INSULATED – why had I had so much trouble? From there it was a short hop to identify the symbol for “Class II electrical appliances”, and a bit of light relief to empty each group of nine cells and add the required further bars. 
For good measure, I then erased all the other bars, but only after checking that the shortened words (VAU, BIS, DAL etc) were in Chambers. I scratched my head for a while about the meaning of “as exemplified by the puzzle’s title” and eventually settled on the simple fact (seconded by fellow bloggers) that the numeral 1900 is 9 (=3 squared) in 100 (=10 squared). That felt rather “Is that it?”. 
I had some fun along the way trying to guess which of the setters set which clues but am confident in only a handful of my guesses. Thanks to them all. (PS I’m afraid that “plugged correctly” in the preamble just passed me by.)
| Clue | Answer | Wordplay | |
| Across | |||
| • | Nocturnal creatures showing a form of pillow worship | WHIPPOORWILLS | [PILLOW WORSHIP]* |
| • | One or other in due course contracted chronic condition | SOME | SO (in due course) ME (myalgic encephalomyelitis, chronic condition) |
| • | Sleek, small-medium pistol? | SMARM | S(small) M(edium) ARM (pistol) |
| • | Cheapest junk avoiding chain stores abroad | ÉTAPES | [CHEAPEST]* ¬ CH(ain) |
| • | Salad crops picked at regular intervals | COS | C(r)O(p)S |
| • | Unionist invested in very old German home of Liebfraumilch? | VAULT | U(nionist) in V(ery) ALT (old, Ger) |
| • | More than one block of salt per house, unusually | EUPHROES | [PER HOUSE]* |
| • | Parachutes descend to earth mostly – reckon to lose last one | DROGUES | DRO(p) (descend to earth) GUES(s) (reckon) |
| • | Ground crew’s tips after pay’s first docked | ERKS | PERKS (tips) ¬ P(ay) |
| • | Charlie enjoying success with stripping | NITWIT | (i)NIT (success) WIT(h) |
| • | Crime punished around prisons | SIN | (pu)NIS(hed) rev. |
| • | China’s rebuffed rebuke | SLAP | PAL’S< (mate’s, china’s) |
| • | See backing bands perform retro song | YODLE | ELY< (cathedral city, see) around DO< (perform) |
| • | Rest of drugs reported | EASE | homophone: E’s (ecstasy, drugs) |
| • | Initially chap, American, held back American chap’s sobriquet | MAC | C(hap) AM(erican) all< |
| • | Increasingly bloody duke overcoming king separated in fighting | REDDED | REDDER (increasingly bloody) with D(uke) replacing R (king) |
| • | Wader remains in the same place in the van | IBIS | IS (remains) after IB (ibidem, L, in the same place) |
| • | Most private son paying a visit? | CLOSEST | S(on) in CLOSET (paying a visit?) |
| • | Couple refusing to accept losing one of digestive tracts | DUODENAL | DUO (couple) DENIAL (refusing to accept) ¬ I (one) |
| • | American generation’s custom | USAGE | US (American) AGE (generation) |
| • | Local party to bar initiator of operations | INN | IN ON (party to) ¬ O(perations) |
| • | Non-British food for magistrates | EDILES | EDIBLES (food) ¬ B(ritish) |
| • | Computer commands? RUN appears in studies | CRONS | R(UN) in CONS (studies) |
| • | Remove human input from task, scrapping unfavourable work surface | DESK | DESKILL (remove human input from task) ¬ ILL (unfavourable) |
| • | Some cells may be so hybrid, split by one inverted wedge | MULTINUCLEATE | MULE (hybrid) around UNIT< (one) CLEAT (wedge) |
| Down | |||
| • | Empty collection of old books into pile | HOT-AIR | OT (Old Testament, collection of old books) in HAIR (pile) |
| • | I’m a socially acceptable leader of Muslims | IMAUM | I’M A U (socially acceptable) M(uslims) &lit. |
| • | Female drapery combining energy with endless desire | PEPLUS | PEP (energy) LUS(t) (desire) |
| • | One’s enthralled by favourite bird in Orkneys | PIET | I (one) in PET (favourite) |
| • | Bearer of flowers repeatedly pruned from bush | OMBU | (f)(r)OM BU(s)(h) |
| • | Violently strike head of pert tomboy once | RAMP | RAM (violently strike) P(ert) |
| • | Bitter of surprising strength I declined | WRY | WIRY (of surprising strength) ¬ I |
| • | To become a senselessly cruel individual, elderly brother usurps power in charge | IMBRUTE | BR(other) for P(ower) in IMPUTE (charge) |
| • | Scarce greens in Arkansas could be close to developing when given time | LOCOES | [CLOSE TO]* ¬ T(ime) |
| • | Impertinence succeeded in interrupting judge | SASSINESS | S(ucceeded) IN in ASESS (judge) |
| • | Noises affected intellectual activity | NOESIS | [NOISES]* |
| • | Plant one found in some mud moved near rear of shed | DESMODIUM | I (one) in [SOME MUD]* after (she)D |
| • | Semiconductor component of audio device | DIODE | (au)DIO DE(vice) |
| • | Young bird’s wing, weak internally and beginning to fail | OWLET | (v)OLET (wing) around W(eak) |
| • | Jock’s allowed sturdy English inside | GIED | GID (sturdy) around E(nglish) |
| • | Bird broods that were not originally very well | NYES | N(ot) YES (very well) |
| • | Gap before food’s taken by moth | LACUNA | AC (ante cebum, L, defore food) in LUNA (moth) |
| • | Rising Elizabethan prince conceals Catholic offspring | PRODUCT | TUDOR (Elizabethan) P(rince) both< around C(atholic) |
| • | Local man finally abused like another by the same parent | CLONAL | [LOCAL (ma)N]* |
| • | The party serving at His Majesty’s pleasure | INSIDE | IN SIDE (the party serving) |
| • | Eat for fun, noisily | INGEST | homophone: IN JEST (for fun) |
| • | Article taking blow on top – something like a helmet? | GALEA | A (article) after GALE (blow) |
| • | Midday, not a single person knocking off early | NOON | NO ON(e) (not a single person) |
| • | Japanese people maintain upper limits | AINU | (maint)AIN U(pper) |
| • | Buccleugh’s second boy raised in Scottish estate | UDAL | (B)U(ccleugh) LAD< (boy) |
| • | Title of respect, one eminent scientists picked up | SRI | I (one) RS (Royal Society, eminent scientists) all< |
I still don’t understand the title….
Nor I. There are two 00s staring at me from the grid, and each of them consist of nine squares in total, and/or each of them have one square at their heart….but none of this seems to add up to anything. Is there some insulation standard labelled IIXC……? Anyway, thanks to HG for parsing MULTINUCLEATE, where I couldn’t see beyond the wedge being something connected with Cuniform in reverse, and to Pink for the puzzle.
Agreed, it was a very poor finish.
The title should have been ‘9, for example, in 100, for example’.
I think the key to the title is the definition of the double insulation symbol.
Wikipedia states that ‘In Europe, a double insulated appliance must be labelled Class II or double insulated or bear the double insulation symbol: ⧈ (a square inside another square)’, so as Holy Ghost says the number 1900 can be described as a square (9) inside another square (100) – 1(9)00
I’m afraid this one fell into the “life is too short” category, but thanks to the setters for expanding my vocabulary and to HG for all that hard work. I’m looking forward to someone explaining the link between 1900 and class II electrical appliances. 1/10 for me this week, as I managed to work out a few answers, and even fit a few of them correctly into the grid.
The main thing I have to say about this puzzle is that it was an excellent example of a jigsaw crossword. I have only just completed it, having found it to be pitched quite high, the lack of enumerations adding to the complexity of the puzzle (particularly at the start) and the time taken to complete it. The clues were to a high standard, and my appreciation of them is my big take-away from this puzzle. I guessed INSULTED would be be made into INSULATED (there was no other possibility), but I had no idea there was a symbol for double insulation, let alone what it looked like.
I liked the way that the erasures left real words, as it must have been quite difficult to accomplish.
Thanks to the PINK team, and to HolyGhost for the blog.
Having worked out it must be ‘insulated’, but wasn’t double glazing, I decided to wait for this website’s elucidation (and it was more straightforward than I supposed!). I did see the potential for a % sign in the grid, which would fit with ‘nine in one hundred’… but endgame apart, I found the filling of the grid extremely challenging and satisfying, working from top and bottom towards the very tricky middle. Thanks to PINK and HolyGhost.
I enjoyed it, although it was super-tough. Blank grids generally give me the heebie-jeebies so this took several visits and half a rubber to crack.
The title made perfect sense to me, as explained by Duncan @4.
Many thanks to PINK and HG.
Tough indeed, but I got there in the end with WHIPPOORWILLS as a useful entry point (after the red-herring pursuit of some variety of OWLS). Many thanks to HG and the components of that awesome gestalt mentality PINK. The title’s “square in a square” made sense to me, if not immediately.
We also found the grid-fill tough, but we expected nothing less from PINK, and we were also rather disappointed in the endgame, if it is just drawing the bars around the two 3×3 sets of empty cells. But Bert then wondered whether PINK’s intention is that we should put more bars in to create two 10 x10 squares around to two 3 x 3s, creating 9 in 100. If we insert bars between the 3rd and 4th rows to the right of the top 3 x 3 square and bars between the 3rd and 4th columns below the top 3 x 3 square, we create a 10×10 square with the lower 3×3 square almost in the middle. Bars can also be added between the 10th and 11th rows to the left of the lower 3×3 square and between the 10th and 11th columns above the lower 3 x 3 square to create a 10 x10 square with the upper 3×3 square almost in the middle. We’re still not sure about this, but it does create two lots of 9 in 100 and maintains the symmetry of the grid. It will be interesting too see how the solution is displayed in Saturday’s i!
Late to the party here, and surprised by the tone of disappointment. Potential puzzle of the year for me.
Did take me way too long to understand that “exemplified by the title” means a square in a square. And much too long to notice that the title is just a description of the puzzle number 1900. So lots of late PDMs for me, that made it so enjoyable 🙂