One of my favourite impro-photo portraits is of Kathleen King taken at the Ashridge AMOC conference last year.

The small, grainy picture is a selection zoomed in from taken from a much larger image.

Kathleen had been describing a particularly difficult time in her work and I asked her to tell me how it felt. She struggled for a few moments and then said, 'Well, it was just incredibly precarious - let me try to show you..."

With that she climbed on to part of the conference projection equipment; a fairly frail wooden box full of computers amplifiers and associated bits of electronica.

Clearly, Kathleen doesn't weigh much but I was beginning to get a feeling for her sense of 'precarious'.

As the audience began to gather I could tell by their expressions that this had the potential to end rather badly....I snapped away rapidly before the whole lectern-thing collapsed into an expensive disaster followed by a rapid trip to casualty.

OK. Time to stop...

I had a feeling of getting something in the camera but wasn't sure what I had captured until I saw it on the computer. After some playing and editing I began to see something like a possibility of the final portrait.

My final, manipulated shot is redolent of a pre-renaissance image - Kathleen as a glowing, saintly presence - though with a curious Mona Lisa styled expression of scepticism.

Kathleen is a leading light in her work and in the programs she runs - and maintains a curious, reflective stance towards her own leadership - like she can't quite believe it.

In fact, maybe the power of this photo is that, in conversation with her, I hear her naturally critical, unassuming stance which means she doesn't quite see herself like this - and that the image doesn't quite ring true for her.

But this is exactly how everyone I have spoken to sees her. Result.