This argument has flared up from time to time since before the second world war! Originally motor bikes had a front plate too, but the then argument was for the smaller motor cycle plates as being more appropriate to a little vehicle. The tricyclists lost the first argument.
As an aside, don't know about motor bikes, but car letter sizes were a bit bigger than today, the size was reduced when the ABC123A format came in as the area taken up was more, and very slightly further when the present AB12ABC format came in.
Currently I think it is fairly safe to say officialdom does not know what it is doing with trikes! The current licensing status whereby new drivers are required to pass all stages of a lengthy motor cycle licence and not allowed to drive one with L plates as an accompanied driver (as you would be with a Ferrari providing you found an insurer) is at least partial witness to it.
A few years ago, I met a number of Grinnall Scorpion drivers and none of them had front plates, but a fair percentage were wearing crash helmets.
If you are required to have a front plate I believe the absence of one currently is only a £30 fine, and non-endorsable. This is perhaps why a fair number of Ferraris are without a front plate - the fine is peanuts to most owners.
So you may decide the likelihood of getting caught is slim, even if one is still needed, and the potential fine is not enough to worry about. The only caveat to this is if the car is sporting a so called personal plate, DVLA may grab it back and re-register your pride and joy forcing you buy new numberplates (two) and perhaps incur an insurance charge to amend the certificate. Although this sanction is normally mentioned in regard to misplaced or distorted digits (ie where 8 ARY becomes Bary) I've not heard a definite case of it being carried out.
