Ifor is back, solo, after his recent doubling up with Nimrod. 
 
Preamble: All across clues, together with those to down entries in odd columns, are normal, but the latter’s answers are each to be entered jumbled to non-words so as to reveal all but one member of a group. The missing member must be named below the grid. Remaining down clues each contain an extra letter to be removed before solving; in clue order these spell two consecutive words from a line in Shakespeare (in ODQ); its concluding words suggest the theme. The two words are also the title of a work by the thematic author. 
With hindsight, I made my job more difficult by thinking the clues were harder than they turned out to be. First couple of times through I solved fewer of the across clues than I might have done, and most of the down answers that I got were for the odd columns so I couldn’t enter them for some time. Nevertheless, the rightmost column looked like it could contain BATTY THOMAS or maybe RATTY THOMAS. That meant nothing to me and the Google hits didn’t look that promising. (Try harder!)
 I plugged away … the extra letters seemed to be heading for ?AH?Y ?IGHT, but that H didn’t look right – it wasn’t.
Anyway, the top right corner yielded and it was definitely BATTY THOMAS I should be searching for, so I Googled again. The trail quickly led to The Nine Tailors by Dorothy L. Sayers; and of course the extra letters should spell GAUDY NIGHT, a title I was familiar with from way back. But now the flood gates were open … TAILOR PAUL, JERICHO, SABAOTH, DIMITY, GAUDE, JUBILEE were speedily slotted in, leaving John as the missing member to be named below the grid.
There were, however, a handful of clues remaining to be solved, mainly those in columns 1, 7, and 11. PARLOUS at 22d was almost immediate, but ABLE-BODIED at 17d took a short while – I was fortunate that the unchecked terminal letter of the entry was so close to the start of the alphabet. IMIDES at 5d took ages; I could see the wordplay (sort of, “over” indicating an anagram is novel?) but couldn’t see a clear link to “Captan”, and there were scores of other possible ways to generate the entry E?SDIM: MEDICS, DEMISE, MIDGES, MISLED, SMILED, DENIMS, MISSED, DEMIST, to list a few of the more common ones. But “Captan” is mentioned in the Wikipedia entry for IMIDE so I settled on that (somewhat grumpily). I suppose that I might have given Ifor more credit – I had noted that 14d had two unchecked occurrences of R, and 17d had two unchecked B’s, so it could have been natural to assume that the second unchecked letter in 5d was another I.
The Shakespeare reference is to Antony and Cleopatra, act 3, sc. 11, and the line ends “Let’s mock the midnight bell.” Thanks Ifor – quite a challenge to get going on this one, and I have yet to pin down quite what the title refers to. Some campanology connection? 
 
Sadly a DNF recorded here this week as more important family matters got in the way and I ran out of time, which was a shame as I was really enjoying this puzzle. I thought it had some well constructed and quite challenging clues. Oh well, can’t be helped.
As well as the clues (which I thought were excellent), I very much liked the thematic design of this puzzle, and in particular (1) the way that the jumbled entries were forced by the crossing letters to be in the correct order for the thematic names and (2) (as noted also by the blogger) the fact that in all three instances where there were two unchecked letters in the jumbled entries those two letters were the same.
My grid was close to completion when I saw JUBILEE, JERICHO and THOMAS fully formed among the jumbled Down entries. I had no idea what the ‘group’ was, but as I already had the name of the author (from GAUDY NIGHT) a simple online search found the source for me, giving me also the missing member JOHN.
Some of the clues to the jumbled entries were quite challenging, and ABLE-BODIED in particular took a long time coming – mainly, I think, because both B’s were missing as well as one other letter for a while. I wondered why PROVOSTS had a misleading enumeration, but it seems it was an error (as also noted above).
Thanks to both Ifor and HolyGhost.
RE: the title, I simply took it to refer to the ‘rocking’ motion of the group of bells when in use, although I might be missing something more precise.
Perhaps on the gentler side for Ifor, but always a satisfying solve.
If it hadn’t been for the lousy weather, I think this would have been a DFN for me as I would have run out of time. I think Rock Hard would have been an appropriate title. Fortunately I did succeed and enjoyed the bumpy ride. As HG observed there were some initially baffling clues which became perfectly clear once the correct parsing had been spotted following a guessed answer. I first saw NIGHT emerging from the down clues but this was no help when using the ODQ index and I needed the GAUDY to access the quote. Then I spotted JERICHO which my wife thought might be the name of a bell but a web search for Jericho Bell just sent me up cul-de-sacs. I have only met (and forgotten) DLS’s work from the TV adaptations so their titles were unfamiliar and I needed the given link to progress further. Unusually, Wiki was unhelpful in finding the required names and it was only by searching “names of the nine tailors” that enabled me to complete the end game.
Thanks to Ifor for an ultimately satisfying ride and to HG for the usual thorough blog.
After a period of popular culture, search engine very much required (and only any use once DLS has been identified); and there was me thinking ‘my sad captains’ came from Them Gunn. Thanks to Ifor and HolyGhost.
A good challenge but definitely less enjoyable than the pop culture ones.
I had DUTTLE for 11a for a while, which didn’t help, but also got there via Batty Thomas and Jubilee. Establishing the theme certainly helped with gridfill, although finishing off the last few anagrams still took some time.
I thought ROCK BAND would have been a better title!
All thanks to Ifor and HolyGhost. I was entirely in the dark until GAUDY NIGHT became clear, and I started thinking of sets of things in Dorothy Sayers — briefly considering and rejecting the six suspects in Five Red Herrings because we needed eight. Of course, it had to be what John Dickson Carr’s Dr Fell once called “the deadly bells of Fenchurch St Paul”, and BATTY THOMAS quickly fell into place. As a Sayers fan I expected to fill in all the bells from memory, but had to go to the book for the missing JOHN. Much enjoyed!
No idea about the theme, so google had to be my friend. Able-bodied was the last one to fall, long after everything else was worked out.
I’ve only just noticed that the NUT in NUTJOB has been left unexplained! That component is defined in the clue as ‘short gap in sentence, perhaps’. It refers to one of the definitions of the noun ‘nut’ in Chambers: ‘an en (printing)’. An en is a measure of, say, a space or symbol or letter of a certain width, being half of an em.
Alan B @9: NUT was explained … but maybe I should have inserted the intermediate step of NUT = “en” = …; now added.
As always, my thanks to blogger and commenters. Regarding the enumeration error, I know how it happened but that’s no excuse – apologies. I hope it didn’t cause too many problems.
One clarification. As has been pointed out, pairs of unchecked cells in jumbled entries each contain the same letter. Editors insist on this, the principle being that the fill should be unambiguous independent of any constraint imposed by the theme.
I’m not a Wimsey fan; his behaviour in the opening chapter of the thematic work makes him in my view the least likeable character whose author didn’t intend him to be so. But all is grist to the setter’s mill.
Ifor @11: thanks for dropping in. And any elucidation on the title? (Have we all missed something?)
Nothing missed, HG; Kippax@3 has it exactly right. I did contemplate “Swingers’ Group” but thought better of it.