This took me 10 minutes, but oon reflection there's nothing unfair or excessively complex. I havent done one by Bob and Margaret before so maybe it's just a wavelength thing. Good mix of clues, nice surfaces. Hard to pick a winner - I like 8ac and also 11dn

Across
1	Some provided source of Latin poetry (4)
	OVID -  hidden word -  prOVIDed
4	Admen had styles personally crafted (8)
	HANDMADE - anagram ('styles') of ADMEN HAD
8	Three of the fifteen best seats? (5,3)
	FRONT ROW - double definition. The front row of a rugby scrum consists of three players, two massive 'props' and a slightly shorter player called a 'hooker' (no laughing across the atlantic), out of the total of 15.
9	Instrument in sack brought back (4)
	TOOL - LOOT backwards
10	Auditor’s punished for discovery (4)
	FIND - sounds like FINED
11	Yellow clay rod somehow bearing weight (8)
	COWARDLY - anagram ('somehow') of CLAY ROD with W for weight inside
12	Judge encounters advocate, finally, when returning (6)
	ESTEEM - MEETS + E all backwards
14	Month that ends too soon for girl (6)
	MARTHA - MAR (month) + THA(t)
16	Hold back from relaxation, then shower (8)
	RESTRAIN - REST + RAIN
18	A number a lot may go for cheaply? (4)
	SONG - 'going for a song' means to sell cheaply
19	Raising agent, heading off in this direction? (4)
	EAST - YEAST minus the 'heading'
20	Father’s host for old TV show (4,4)
	DADS ARMY - barely cryptic.
22	Road-edge spoiled, with battered corners (3-5)
	DOG-EARED - anagram ('spoiled') of ROAD EDGE
23	Eagle sailors found in middle of Greece (4)
	ERNE - sailors are RN (Royal Navy) inside EE (middle of 'Greece')

Down
2	Maids serving King drink within six seconds (7)
	VIRGINS - King is R, drink is GIN. All contained within VI (six) S (seconds)
3	Ate in study I’d set up (5)
	DINED - DEN ID reversed
4	The girl’s seeing the earl regularly (3)
	HER - alternate letters of tHe EaRl
5	She has the latest snowman we built (9)
	NEWSWOMAN - anagram ('built') of SNOWMAN WE
6	Older erratum corrected (7)
	MATURER - anagram ('corrected') of ERRATUM
7	Amusing conclusion to repeated spin (5)
	DROLL - D (last letter of 'repeated') + ROLL (spin)
11	Someone who arrives holding mike, with officer in charge? (9)
	COMMANDER - Someone who arrives is a COMER, with M (Mike, phonetic alphabet) + AND (with) inside
13	On reflection, some felt it needed permit (7)
	ENTITLE - 'some' = hidden word klaxon. This one is reversed: fELT IT NEeded
15	Game where the suspense comes at the end (7)
	HANGMAN - cryptic definition
17	Books are turning up inspirational source (5)
	ERATO - OT (old testament ) + ARE all backwards. One of the Muses of Greek and Roman mythology.
18	Good fellow on the beer becoming overfamiliar (5)
	STALE - ST (good fellow) + ALE
21	Detective having daughter carried out (3)
	DID - DI (Detective Inspector) + D

I thought we were in good hands with this Jumbo, which was fairly chewy and really rather enjoyable - thanks setter! 50ac was quite possibly the last one in due to being an unfamiliar expression, though there were a good few others that took a while to "see" as well. My favourite this time possibly 15ac, simple but very neat; but 19dn is rather nice too, and not even the only excellent-sounding hat in this puzzle.

How'd you all get on?

ACROSS
1 Like an old maid with unserviceable cooker (6)
PRIMUS - PRIM [like an old maid] with U/S [unserviceable]

5 Scraps a few words in speech (7)
AFFRAYS - homophone of A PHRASE [a few words]

9 Check canine? (8)
DOGTOOTH - double def - though my dictionary app lists the tweedy check pattern as dog's-tooth. Close enough anyway.

13 Dreadfully crude cuts in Manchester, due to conditions (5,3,13)
UNDER THE CIRCUMSTANCES - (CRUDE CUTS IN MANCHESTER*) ["dreadfully"]

14 Bombardment on town primarily, then country (8)
THAILAND - HAIL [bombardment] on T{own} + AND [then]

15 Part of mechanism leaking fluid (7)
LINKAGE - (LEAKING*) ["fluid"]

16 Co-ordinated report of high water? (4,2)
TIED IN - homophone of TIDE IN [from which intelligence we can assume high water]

17 A close relative cutting exercise, so it seems (10)
APPARENTLY - A + PARENT [close relative] "cutting" PLY [exercise]

20 Eastern weapon for shooting a politician revealed in correspondence (12)
EPISTOLATORY - E PISTOL A TORY [eastern | weapon for shooting | a | politician]

23 Hat requiring some dagger-like pins (4)
KEPI - hidden in {dagger-li}KE PI{ns}

24 Diplomatic prison guard briefly incarcerated by regime (8)
DISCREET - SCRE{w} [prison guard "briefly"] "incarcerated" by DIET [regime]

26 Two locals, the first in California to find mineral (8)
CINNABAR - INN and BAR [two locals], the first of which is in CA [California]

29 Tam-o-Shanter's super-hot pepper? (6,6)
SCOTCH BONNET - the hot pepper's name suggests an item of Scottish headgear, which the Tam is

30 Break forth and flee Forces in disarray (10)
EFFLORESCE - (FLEE FORCES*) ["in disarray"]

32 Take off over area of grassland and bush (4,6)
MOCK ORANGE - MOCK O RANGE [take off | over | area of grassland]

34 Enthusiastic supporters boost government’s morale? (12)
CHEERLEADERS - or CHEER LEADERS [boost the morale of | government]

36 US psychiatrist that is ultimately seen amid toprankers (8)
ALIENIST - I.E. [that is] + {see}N, amid A-LIST [toprankers]

38 Cake covering when swathed in sauce (8)
SOLIDIFY - LID IF [covering | when] "swathed in" SOY [sauce]

39 Eleven motorists cross about origin of journey (4)
AJAX - AA X [motorists | cross] "about" J{ourney}. Eleven as in a football side, of course.

41 Because airport's close, our home proved extremely expensive (4,3,5)
COST THE EARTH - 'COS [because] + {airpor}T + THE EARTH [our home]

43 Doctor chips in, say, for his colleagues? (10)
PHYSICIANS - (CHIPS IN SAY*) ["doctor"], semi-&lit

44 When one lacks power, there's no resistance in assault (6)
OUTAGE - take OUTRAGE [assault], and remove R = resistance

46 An attempt on record broken by any number in the past (4,3)
LONG AGO - A GO [an attempt] on LOG [record] "broken by" N [any number]

48 Disorganised gaggle regularly roaming harbours (8)
STRAGGLY - G{a}G{g}L{y}, harboured by STRAY [roaming]

50 Seize the chance to linger canal-side? Without warning of course (4,4,2,3,8)
TAKE TIME BY THE FORELOCK - TAKE TIME BY THE LOCK [linger canal-side], "without" FORE! [warning of (golf) course]

51 Pest controller ceaselessly campaigning? (8)
WARFARIN - WARFARIN{g} ["ceaselessly" campaigning]

52 Customer from the States coming in closer? (3,4)
END USER - US [the States] "coming in" ENDER [closer]

53 Overcoming strong smell, I'm going back inside (6)
TAMING - TANG [strong smell], with I'M reversed inside it

DOWN
2 Uneven grating below par (5)
ROUGH - triple def, referring perhaps to ground, a voice, and a person with a hangover perhaps, respectively

3 Singer from capital appended to unbalanced schedule (11)
MADRIGALIST - RIGA [capital] appended to MAD [unbalanced], plus LIST [schedule]. Took a while for me to realise the capital wasn't Madrid.

4 Talk of banker, fired, having additional liabilities (8)
SURTAXED - homophone of CERT [banker, as in "a sure thing"] + AXED [fired]

5 Did long account on hard press chief (5)
ACHED - AC [account] on H ED [hard | press chief]

6 Memory possibly defective, Charlie admitted (7)
FACULTY - FAULTY [defective], "admitting" C

7 Energy-packed FBI agents, in absolute terms (11)
ARRANGEMENT - G-MEN [FBI-agents], "packing" E [energy], in ARRANT [absolute]

8 Very much America's March man? (5)
SOUSA - SO USA [very much | America]. Marches as in military music. Sousa was not just a March man but The March King!

9 Depict spy hilariously out of humour (9)
DYSPEPTIC - (DEPICT SPY*) ["hilariously"]

10 19th century president's allowance (5)
GRANT - double def

11 Arrange theatre score? Just about? (11)
ORCHESTRATE - (THEATRE SCOR{e}*) ["arrange"], &lit

12 More crusty deposit raised bank (7)
TESTIER - reversed SET [deposit] + TIER [bank]

18 Coach supports gym, limiting runs in early years (9)
PRESCHOOL - SCHOOL [coach] supports P.E. [gym] "limiting" R [runs]

19 Hat in good condition obscuring male ears? (7)
TRICORN - TRI{m} [in good condition, minus M for male] + CORN [ears]

21 Winning entailed galloping astride horse (2,3,4)
IN THE LEAD - (ENTAILED*) ["galloping"] "astride" H [horse]

22 Outsider welcomes teacher being in capital (8)
LONDONER - LONER [outsider] "welcomes" DON [teacher]

25 Criminal retreats with engineer's coat — could it add to the charge? (9)
CONDENSER - CON DENS [criminal | retreats] + E{nginee}R. AKA a capacitor.

27 Establish a spot to house country's first queen (9)
ASCERTAIN - A STAIN [a spot] to "house" C{ountry} + E.R.

28 Correct delivery is taken in by ruler without delay (8)
SHARPISH - R.P. IS [correct delivery, sez some | is] "taken in by" SHAH [ruler]

31 Light horse-drawn carriage: a crawler? (7)
FIREFLY - FIRE FLY [light | horse-drawn carriage]

33 Follow detailed instruction to avoid crossing railway line (4,5,2)
KEEP TRACK OF - take KEEP OFF [instruction to avoid], de-tail it, and put it across TRACK [railway line]

34 Harsh complaint impassioned with king's intervention (11)
COLDHEARTED - COLD [complaint] + HEATED [impassioned] with R [king] "intervening"

35 Scene of life class, maybe, where guests are entertained? (7,4)
DRAWING ROOM - or a room in which more literal drawing is taking place

37 Dad instructed staff, introducing Higher Education (3,3,3)
THE OLD MAN - TOLD MAN [instructed | staff], "introducing" HE [Higher Education]

40 Strongest church beset by strife, suffering (8)
FIERCEST - CE [church] "beset by" (STRIFE*) ["suffering"]

42 Top of oak stake tipped prime cactus (7)
OPUNTIA - O{ak} + PUNT [stake, as in wager] + A1 [prime] tipped over

43 Use IT perhaps to handle move in train (7)
PROCESS - double def

45 When territorial guards submit? (5)
ENTER - "guarded" by {wh}EN TER{ritorial}

47 Lord's swipe — one bye conceded (5)
NOBLE - NOB{b}LE [as in "get hold of illicitly"], "conceding" one B for bye

48 Thoroughly clean comb (5)
SCOUR - double def

49 Compare Liberal president with nation's leader (5)
LIKEN - L IKE [Liberal | president] + N{ation}