Finally got to the end - I'm completely underwhelmed - Yes it's a neat construction and yes it illustrates a nice proof but like many a listener completely lacking in humour in the endgame.
I do have the two nine letter words in what I think is the correct position (after all it's only fifty-fifty!) and a few other clues intersecting with them in a satisfying manner, but it will take quite a few more cold solves to make substantial progress.
In a way The Listener is not a crossword in so far as the setters take pains to make it difficult to intuit solutions from crossing letters
Phew! Just finished the beast and I've calculated that I've spent at least a day of my life in the process! Barretter (or anyone else who's been struggling like me) - if you want help, just post here.
I think I need too much on this one, only 11 clues done ( 2 of those thanks to this thread ) wish I knew which ones are the definition misprints, at least grid B was easy.
unclued, many thanks for your help, I have now been able to fill about third of grid, can I trouble you one last time to confirm or otherwise that these are the nos between 27 and 48,
30, 32, 33, 34, 40, 41, 44, 47, 48, plus 3 more?
Notwithstanding the rancour in this thread, I'll add my thruppence. Ciderdotndave asked for a hint, not an answer. I'd hoped my 'it's an anagram less 2' wasn't too blindingly obvious. I feared it went too far for the question. I certainly didn't think the question was 'what's the answer' - which this site allows (as if it couldn't) - and I'd liked the request for a hint rather than the answer; why do crosswords otherwise? The response to my request for a hint on the final step was precisely calibrated, and fair. I'd like to think I'd have got there anyway, but it gave me confidence to start tearing it all up for the final step.