The M3W V5 says "Tricycle" so you would think that things that refer to Tricycles in the DVLA rules would maybe apply to Tricycles.....but we are talking about a government organisation here.
The key thing for the regulations is the V5 item J where the vehicle category is L5 - which it is by dint of having a Three Wheel wheelplan(D4) and a Tricycle body type (item d5)!
I've also just noticed on the V5 item P2 says max net power is 50Kw (about 67bhp) !