Such as??
The /5s have more bobs that they have bits.
I'm not sure actually why.
Hmmmm well, after reading on wiki - it said something about them being dual voltage??
But I thought most of them were anyways?
377/2
377/5
375/6
Are the only subclasses that are dual voltage.
Correction in bold. Sorry for the late response.
BTW, this Vehicle Change doc. mentions the reason for the additional sub-class designation:
If the trains involved are class 377/5 they will be a new build yet to enter service which will be based on Class 377/2 in design, with minor changes such as new toilets and an improved OTMR.