If you want to e-mail Tristan use the CONTACT WEBMISTRESS form and I'll forward the e-mail on to him direct - I can't guarantee a reply, but I can guarantee that he'll read your message.
You can Tweet him via his ID of @TristanGemmill - again, no replies guaranteed.
You can write to him via his Agent - please include a SAE if you want a signed photograph or reply - which is not guaranteed.
Tristan Gemmill
c/o Independent Talent Group Ltd
40 Whitfield Street
London
W1T 2RH
I can forward mail on to him quicker if you'd like to send post via me so I can forward it on - I have his home address, but you'd need to pay forwarding mail cost - mail to his Agent can take months to get to him. Message me via CONTACT WEBMISTRESS form.