One of the cool things about the Berk T60 was locking out reverse was as easy as placing a tab over the linear shift quadrant... easily disabled for someone with a full license...
They never officially offered the three wheeler Berk with the Enfield motor, but it was a really easy swap as long as you had the four wheeler B95/B105 bonnet and front clip to cover it.
My T60 feels like you're going to go airborne at 65mph... I can't imagine a three wheeled Enfield model at the claimed 105mph!!
I also had a T60 with a Mini Cooper 1275 up front. These are stunningly fast, but hidelously ugly and poor handling....
(At one point there were 12 known Berk T60's in the US and I owned 4 of them... back down to just my original).
While we're talking UK strange stuff... I had an AC Acedes MK12 invalid carriage circa 1965. (yes the same folks who made the Cobra). these were given to the disabled by the National Health Service.
It had an all-alloy body, used a single cylinder Villiars engine in the rear driving only one rear tire. Single wheel up front. All hand controls, no pedal.
Twist throttle, hand clutch, forward to trun right, back to turn left, down for brakes. Four speed shifter on the right side. For reverse, you pulled a lever which killed the engine and restarted it in reverse. Then you had 4 reverse gears!
No bumpers.
If it handled at speed like my Bond Bug (I never did more than move it around the garage) I frankly can't think of a much more unsafe car to give a disabled senior!!
It and my Bond Bug now reside in other collections... I'll take my three wheels with the single wheel in the rear, thanks!
Bill