Well, that was by far the most difficult one since I started the online versions about 5 weeks ago. Printed on the Saturday while in France, so no solving aids, although it helped that younger daughter (who inherited the crossword gene) was around for 2 days. I do think we 'lone solvers' are at a bit of a disadvantage in that respect. Since then it has been on another trip with me and I eventually finished it this morning (shows it must be about at the limit of my ability I suppose). Theoretically should be in time to submit, but hold out little hope of Royal Mail delivering to St Albans from deepest Dorset by tomorrow, so will save the price of a first class stamp.
Many thanks to Elgin for a most enjoyable and extremely clever puzzle.