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
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.