I sent a letter, fan-art, and 2 IRCs
I recieved a signed photo.

Sent : 25 Feburary 2013
Recieved : 9 May 2013

Address used:
Freddie Highmore
ARG
4 Great Portland Street
London W1W 8PA
UK

I sent a letter, three photos, fan-art, and 2 IRCs
I received three signed photos

Sent: 27 March 2013
Received: 07 May 2013

Address used:
Skandar Keynes
Hamilton Hodell
5th Floor
66-68 Margaret Street
London W1W 8SR
UK