Class 142 subclasses?

[43096]

I think in the 158 case there is some logic. If you look at all the Sprinter fleets together (Class 150 to 159) the vehicle numbering for driving vehicles is 52xxx and 57xxx.

The vehicle numbers are associated with the set number, so you end up with:

●Class 150 = 520xx/521xx/522xx
●Class 153/155 = 523xx
●Class 156 = 524xx/525xx
●Class 158/159 = 527xx/528xx/529xx

So the only gap is the 526xx series (kept for something that was never built?). All this means that Regional Railways, as was, had a logical set of numbers for the bulk of the fleet, with the third digit of the vehicle number identifying the fleet type.

Had the Class 151 prototype not been built it might have been possible to split the Class 150 fleet in Classes 150,151 and 152.

Class 150/0 are not 520xx but 5520x-5540x-5530x.

 

[Sm5]

How many other cases are there of the subclass not matching with the 4th digit (3rd for locos)? Is it just 142s?

Class 92 for Caledonian is an obvious sub class that doesnt exist.