OK, ground to a halt. All complete apart from the SE quadrant where all I have are the letters in 13D. I have 9 of the 12 'special' solutions. I've worked out 23/25 and also the 2 other "possible locations", although I'm missing the last 3 letters of the first and the last 2 letters of the second.
I'm guessing that 28A, 20D and 21D will be the remaining 3 of the 12 'special' solutions. Could anyone confirm that please?
I have an answer for 19A but have no idea how to parse it.
Finally, to kick-start my solving could someone please give me a HINT (NOT the answer) to 24A?
Very grateful for any help.