This is bugging me big time.
It was a TV movie I think made for kids, it featured a boy with a magic T-Shirt.
The T-Shirt had a tigers head on the front and enabled the boy to run faster, be stronger that sort of stuff.
I loved this film but can never remember is name.
Please help me, because if no-one knows the name of this movie I might have a mental breakdown.

I think this might have been "SAMMY'S SUPER T-SHIRT"
Sounds like it was a Children's Film Foundation film. I do remember it. I found a website that lists nearly all the films they made.

http://tv.cream.org/lookin/cff/

I used to watch them as a kid in school every wedsnesday after school at our "movie" club. 30pence a time. Money well spent. I enjeyed them all. Even the ones with Keith Chegwin. Hope this is what you were after.