I just found a rather large amount of images on 59124 at the International Bugatti Trust Register, which provided a wealth of other information (thank you, Herman). I have two questions from my findings:

1. What is the circular thing on the outside left of the cockpit?
2. Is that vertical rod inside the cockpit really the shift lever? Looks shorter and straighter than I've seen.

The circular thing is a holder for the circular disc printed with the car details and use date showing that road tax has been paid to drive on english roads.
basically a tax disc holder giving details of car and expiry date of certificate.

Thank you.