If you would like to help out in your capacity as a physio at the London Marathon, you might like to contact the ACPSM (Association of Chartered Physiotherapists in Sports Medicine) as I am sure they would be able to direct you to whoever you need to speak to:

The details for the Chair of the group are as follows:

Mrs Lynda Daley
Weaver's Lodge
65 Station Road
Castle Donnington
Derbyshire DE74 2NL

I hope this helps
Ron