G'day gideon,
Mine is a '69 Type 54.
Strange . . I've never seen those bevelled holes.
The whole colour thing is intriguing. I've seen some that were darker and some lighter and just put it down to what might have been available at the time.
I don't know where the OEM dash material originated but I suspect it was from a veneered panel of some sort - perhaps originally intended for furniture? - dunno. That might explain why they don't last too well in a hostile environment like a car.
It may also explain JasonH's point about veneer not being available in the full width. That said, wider veneer might have been more available back in the day, but I don't expect the Lotus factory were gluing down veneer, in any case.
Curiouser and curiouser.
Here's a pic of mine. All I can say is that it's pretty close to the original colour and grain . . whatever that was.