I suppose it's related to these Bentleys?:
http://www.autopuzzles.com/forum/2011-39/solved-what-car-206-1978-bentley-donington-special/msg400676/#msg400676The mis-spelling of Donington is daily. I've even seen it mis-spelt on official literature; I suppose the printers thought just one 'n' looked wrong so added another for good measure!
Here is a typical example from an advertisement:
QUOTE
1952 Bentley MkVI Donnington Roadster for saleBentley Mark VI Donington Special
Reg Nr NLC829 Chassis B260SR
Back in the 1970's a company called Johnard Vintage Cars of Blandford, Dorset. re-bodied a number of 1950's Bentley Mark VI standard steel cars with light roadster bodies.
UNQUOTE
As you can see they've spelt it both ways just to make sure! At least they know it's right 50% of the time that way...
The cars were, of course, named after Donington Park race track.