Ah you are THE David Byrden of Tiger I info a site I have used many times in my Tiger build.

Haynes Tiger book page 90 “Driving Tiger 131” by Darren Hayton, he is Dutch and works as an Astrophysicist he has been a volunteer at the tank museum for 17 years and has closely followed the restoration of the Tiger, he is particularly interested in the engineering design and operation of the Tiger.

First impressions.
“From the moment you get in through the drivers hatch you realise that the Tiger is unlike any other vehicle of it’s era. Firstly, the hatch is offset from the seat making it near possible to drive the tank with your head out of the vehicle”.

The above is a word for word extract from the book, “near impossible” is probably a word I should have used however the book does not go any further to how they came to the conclusion, so armed with your diagram that I will need in the future I conducted an experiment with my car what I did learn was that IF the driver could achieve this then he would have to have both arms out of the hatch to support his weight not shown in your picture then there is the matter of the sponson and the hatch and also steering the tank, I have dismissed having a box on the seat to support his weight as this would have to be placed once he got the tank going and removed when negotiating corners so a third party would have been required to aid the driver, my conclusion was that the only way to know for sure is to conduct an experiment in a real Tiger, the chances of this happening at Bovington are next to nil, a friend and I are planning a trip to Saumur, this was planned if we could have access to the Tiger unless on one of your visits you have done this.

David, if you have contacts at Saumur and are willing to travel to the museum then perhaps we could document this matter, my friend John is fluent in French so the language would not be a problem.