I never knew mark in real life, or over the phone for that matter, and thats my loss, but I did converse via the odd thread and I think we PM'd once.

My one vivid memory is after reading all his exploits and adventures, seeing a thread up with some pics of him and some work he had been doing at home, and of he and his microlight and I had to do a double take, I was utterly gob smacked that this behemoth of a man was stuck in a wheelchair.
I hadn't a clue and wouldn't have guessed in a million years.
As someone else who is disabled but with even more limited mobility I found mark and inspiration as I'm sure many others both disabled and able bodied did and still do.
I'm sure marks memory will live on in many different ways, but for me I can't hear or see a microlight without seeing that picture of him next to his with a beaming grin on his face.