Of course, but the hassle can be considerable since vehicle type approval is also necessary before registration will be considered. If it isn't listed with the DVLT or there's no SVA with the application it can't be registered.
As for the vehicle class the way to go is to use the same one as the Reliant Robins, three wheeler car without reverse gear. That way if one has a motorcycle driving licence you're ok, or if you have any car driving licence you're ok.
Registered as a motorcycle trike could mean a CBT is necessary, a pain if a motorcycle licence isn't already held.
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