Scott the Piaggio MP3 is classed as a motorcycle & thus does not need a front plate. The M3W is classed PLG ie a car so I reckon it does need a front number plate.
I had a MP3 which I traded for the M3W. On one occasion took it to a MOT tester that does bikes & they refused as it has 3 wheels. Took it to somewhere that does trikes & bikes & they said first place was talking cobblers.
Tim