I sent a LOR & SASE on the 13.6.12.
I got back in my SASE a signed picture on the 11.7.12
Took 28 days.
Address I used was:
Jessica Ennis
JCCM Ltd.
Matrix Studios
91 Peterborough Road
London
SW6 3BU
Really happy I got a autograph back off Jess.

Picture: http://imageshack.us/photo/my-images/685/001ooom.jpg/