IT began as a minor irritant at the end of a great day on Bidean nam Bian. It was the beginning of summer as I wandered down through Coire an Lochan and became aware of an irritating pain on the inside of my knee. Within a couple of days the pain had reduced to a dull ache. A couple of weeks later I was filming with the BBC on the Isle of Arran. As part of the programme we climbed Goat Fell and such is the nature of filming that we took our time, stopping every so often to position…