I think that Simon already has some artwork that could be used. on a personal note i feel that a 50mm x 250mm sticker is a little large! that is 2 inches wide and 10 inches long. i am sure that forum memberes will want to leave the sticker on the car and something like a tax disc or MGOC badge would be better they are 75mm diameter.
Great Idea
Feel free to play with the logo.
And the photoshop file if thats your thing
tbarlogo.psd
if you're in an MG-R or other longbridge-built car then you park on the grass hill in the park