So, quick update, bought a twin mic like this:
https://www.amazon.co.uk/dp/B01EFEI7..._IARcBbZ58W1TJ
Had to strip the unit down as there wasn’t a surface mount 3.5mm socket. Just soldered in a fly lead to the red and black mic connections on the PCB at the front.
Positioned a mic at the top of left and right A posts. Now sounds great. Very pleased, we’ll worth the efforts.
Tim