I thought this was good and commendably Friday-hard, with the tough combination of (a) very few definition parts that immediately suggest their answers and (b) very few completely straightforward wordplay parts. It may turn out to have been a wavelength puzzle and if so it's one that I surely wasn't on - I still don't understand 1ac, for starters, which I stared at for long minutes before submitting last night. Someone put me out of my misery on that one please...
FOIs 18ac and 24ac probably, 15ac might have been pretty quick to arrive too but I can't remember for sure. LOI (apart from the hippo drop) the unfamiliar archaic term at 27ac. I really liked the straightforward elegance of 21ac; Agatha Christie made a guest appearance in Doctor Who about a decade ago, but I must point out that hardcore Doctor Who fans will get miffed if you call it Dr Who, as 25ac comes perilously close to doing!
The surfaces all hold up in the cold morning light and there is definitely some inventive stuff going on with the multiple cryptic definitions and &lits. 12dn is my Clue of the Day for being a really clever re-interpretation of a cliched phrase that we all take for granted, pointing our poor brains off in the wrong direction entirely. Very glad not to have any ambiguity at all about the spelling of 1dn: I like to think of myself as a very good speller, but HOUYHNHNM lies outside even my confidence zone. Imagine how many "scare the horses" comments it could have generated as an anagram! Thanks to the setter for generally not sparing the horses though, 1-0 to you this Friday I'd say, sir or possibly madam. Grr!
ACROSS
1 What township police would need? (5)
HIPPO - hidden quite obviously inside {towns}HIP PO{lice}, but I still don't get it. Hippos are just the ponderous semiaquatic African mammals, and township police and just township police, aren't they? I never thought the twain would meet. ETA: a Hippo is an Armoured Personnel Carrier used by South African police. Which I guess it probably had to be really. But I did like the idea of them needing an actual hippo. Another &lit eh!
4 Vessel’s very unusual coupling hooks (6,3)
LOVING CUP - V, "hooked" by (COUPLING*) ["unusual"]
9 North Eastern hotel, full up, sadly offering no accommodation (9)
UNHELPFUL - (NE H FULL UP*) ["sadly"]
10 Absurd sentimentality about distant land (5)
GONZO - GOO [sentimentality] about NZ [= New Zealand = distant land]
11 In private, I agree to receive Republican minister (4,9)
HOME SECRETARY - HOME [in] + SECRET [private] + AY [I agree] "to receive" R [Republican]
14 Large piece of skin ought to be put back evenly (4)
HUNK - the even letters of {s}K{i}N {o}U{g}H{t}, reversed
15 Company department whose business is first to pick up? (4,6)
CALL CENTRE - cryptic def, the call centre being the part of the business that fields incoming phone calls
18 Flowers a symbol some mostly abandoned (3,7)
MAY BLOSSOM - (A SYMBOL SOM{e}*) ["abandoned"]
19 Place such as Washington wouldn’t do for everyone (4)
LIEU - LIE [such as (George) "I cannot tell a lie" Washington wouldn't do] + U [for everyone]
21 Position, say, in which murder committed (6,7)
ORIENT EXPRESS - ORIENT [position] + EXPRESS [say]
24 Demanding return of books: we’re disgusted (5)
TOUGH - OT [books] reversed + UGH! [we're disgusted]
25 Who, perhaps, uses it’s elaborately turned out? (5,4)
DRESS SUIT - DR [Who, perhaps] + (USES IT'S*) ["elaborately turned out"], &lit.
27 One that can suddenly drop a clanger, speaking in cheap theatre (5,4)
PENNY GAFF - PENNY [one that can suddenly drop] + homophone of GAFFE [a clanger, "speaking"]
28 Ship touring Caribbean’s in race (5)
SWISS - SS [ship] "touring" WI'S [Caribbean's]
DOWN
1 Cases of hitherto ugly, half-forgotten Hanoverian mares appearing in fabulous horse race (10)
HOUYHNHNMS - H{ithert}O U{gl}Y H{alf-forgotte}N H{anoveria}N M{are}S. The civilised talking horses from Swift's Gulliverian fable.
2 Old man’s audible exclamation of contempt (3)
PAH - homophone of PA [old man "is audible"]
3 Russian department closing after student departed (6)
OBLAST - LAST [closing] after OB [= old boy, student departed]
4 Body drawing from biography about girl (4,5)
LIFE CLASS - LIFE C LASS [biography | about | girl]
5 Brussels throne room turned up treasure (5)
VALUE - EU LAV [Brussels | throne room] reversed
6 Row when entering eg on a fancy here? (2-2,4)
NO-GO AREA - OAR [row], when entering (EG ON A*) ["fancy"], semi-&lit.
7 Civil engineer incorporating fellow’s jolly design (5,6)
CANDY STRIPE - CE [civil engineer] "incorporating" ANDY'S TRIP [fellow's | jolly]
8 One holding chair for piano opposite (4)
PROF - FOR P [for | piano] reversed. ETA: Anonymous's parsing is even better! PRO [for] + F [= forte = piano's opposite]. Thanks anon!
12 Reserve ready for the match? (5,2,4)
MONEY TO BURN - cryptic def, money to burn being money you have in "reserve", that theoretically you could happily take a "match" to...
13 Needs about a pound when daughter’s going places (10)
REQUISITES - RE [about] + QUI{d} [a pound, "when (D for) daughter's going"] + SITES [places]
16 Behold ring being used to bind each type of folder (5-4)
LOOSE-LEAF - LO [behold] + O [ring] + SELF [being] used "to bind" EA [each]
17 Whacking small boy could end in outcry (8)
ALMIGHTY - AL [small boy] + MIGHT [could] + {outcr}Y
20 The works of O Henry missing from promotions? (6)
OPUSES - O + PUS{h}ES ["(H for) Henry missing from" promotions]
22 Girl climbing a mountain finally needing a hand up (5)
NADIA - A {mountai}N reversed ["climbing"], + AID [a hand] reversed ["up"]
23 Over from a spinner (4)
ATOP - A TOP [a | spinner]
26 Reading maybe for which one has no time (3)
UNI - UNI{t} [one "has no (T for) time"]
FOIs 18ac and 24ac probably, 15ac might have been pretty quick to arrive too but I can't remember for sure. LOI (apart from the hippo drop) the unfamiliar archaic term at 27ac. I really liked the straightforward elegance of 21ac; Agatha Christie made a guest appearance in Doctor Who about a decade ago, but I must point out that hardcore Doctor Who fans will get miffed if you call it Dr Who, as 25ac comes perilously close to doing!
The surfaces all hold up in the cold morning light and there is definitely some inventive stuff going on with the multiple cryptic definitions and &lits. 12dn is my Clue of the Day for being a really clever re-interpretation of a cliched phrase that we all take for granted, pointing our poor brains off in the wrong direction entirely. Very glad not to have any ambiguity at all about the spelling of 1dn: I like to think of myself as a very good speller, but HOUYHNHNM lies outside even my confidence zone. Imagine how many "scare the horses" comments it could have generated as an anagram! Thanks to the setter for generally not sparing the horses though, 1-0 to you this Friday I'd say, sir or possibly madam. Grr!
ACROSS
1 What township police would need? (5)
HIPPO - hidden quite obviously inside {towns}HIP PO{lice}, but I still don't get it. Hippos are just the ponderous semiaquatic African mammals, and township police and just township police, aren't they? I never thought the twain would meet. ETA: a Hippo is an Armoured Personnel Carrier used by South African police. Which I guess it probably had to be really. But I did like the idea of them needing an actual hippo. Another &lit eh!
4 Vessel’s very unusual coupling hooks (6,3)
LOVING CUP - V, "hooked" by (COUPLING*) ["unusual"]
9 North Eastern hotel, full up, sadly offering no accommodation (9)
UNHELPFUL - (NE H FULL UP*) ["sadly"]
10 Absurd sentimentality about distant land (5)
GONZO - GOO [sentimentality] about NZ [= New Zealand = distant land]
11 In private, I agree to receive Republican minister (4,9)
HOME SECRETARY - HOME [in] + SECRET [private] + AY [I agree] "to receive" R [Republican]
14 Large piece of skin ought to be put back evenly (4)
HUNK - the even letters of {s}K{i}N {o}U{g}H{t}, reversed
15 Company department whose business is first to pick up? (4,6)
CALL CENTRE - cryptic def, the call centre being the part of the business that fields incoming phone calls
18 Flowers a symbol some mostly abandoned (3,7)
MAY BLOSSOM - (A SYMBOL SOM{e}*) ["abandoned"]
19 Place such as Washington wouldn’t do for everyone (4)
LIEU - LIE [such as (George) "I cannot tell a lie" Washington wouldn't do] + U [for everyone]
21 Position, say, in which murder committed (6,7)
ORIENT EXPRESS - ORIENT [position] + EXPRESS [say]
24 Demanding return of books: we’re disgusted (5)
TOUGH - OT [books] reversed + UGH! [we're disgusted]
25 Who, perhaps, uses it’s elaborately turned out? (5,4)
DRESS SUIT - DR [Who, perhaps] + (USES IT'S*) ["elaborately turned out"], &lit.
27 One that can suddenly drop a clanger, speaking in cheap theatre (5,4)
PENNY GAFF - PENNY [one that can suddenly drop] + homophone of GAFFE [a clanger, "speaking"]
28 Ship touring Caribbean’s in race (5)
SWISS - SS [ship] "touring" WI'S [Caribbean's]
DOWN
1 Cases of hitherto ugly, half-forgotten Hanoverian mares appearing in fabulous horse race (10)
HOUYHNHNMS - H{ithert}O U{gl}Y H{alf-forgotte}N H{anoveria}N M{are}S. The civilised talking horses from Swift's Gulliverian fable.
2 Old man’s audible exclamation of contempt (3)
PAH - homophone of PA [old man "is audible"]
3 Russian department closing after student departed (6)
OBLAST - LAST [closing] after OB [= old boy, student departed]
4 Body drawing from biography about girl (4,5)
LIFE CLASS - LIFE C LASS [biography | about | girl]
5 Brussels throne room turned up treasure (5)
VALUE - EU LAV [Brussels | throne room] reversed
6 Row when entering eg on a fancy here? (2-2,4)
NO-GO AREA - OAR [row], when entering (EG ON A*) ["fancy"], semi-&lit.
7 Civil engineer incorporating fellow’s jolly design (5,6)
CANDY STRIPE - CE [civil engineer] "incorporating" ANDY'S TRIP [fellow's | jolly]
8 One holding chair for piano opposite (4)
PROF - FOR P [for | piano] reversed. ETA: Anonymous's parsing is even better! PRO [for] + F [= forte = piano's opposite]. Thanks anon!
12 Reserve ready for the match? (5,2,4)
MONEY TO BURN - cryptic def, money to burn being money you have in "reserve", that theoretically you could happily take a "match" to...
13 Needs about a pound when daughter’s going places (10)
REQUISITES - RE [about] + QUI{d} [a pound, "when (D for) daughter's going"] + SITES [places]
16 Behold ring being used to bind each type of folder (5-4)
LOOSE-LEAF - LO [behold] + O [ring] + SELF [being] used "to bind" EA [each]
17 Whacking small boy could end in outcry (8)
ALMIGHTY - AL [small boy] + MIGHT [could] + {outcr}Y
20 The works of O Henry missing from promotions? (6)
OPUSES - O + PUS{h}ES ["(H for) Henry missing from" promotions]
22 Girl climbing a mountain finally needing a hand up (5)
NADIA - A {mountai}N reversed ["climbing"], + AID [a hand] reversed ["up"]
23 Over from a spinner (4)
ATOP - A TOP [a | spinner]
26 Reading maybe for which one has no time (3)
UNI - UNI{t} [one "has no (T for) time"]