Don't forget 620, 750, etc.
>QR some classes roughly equalled horsepower and some didn't. Road numbers
>began at 00 except the 1502 class.
Not quite. There was the sole member of the 1225 class.
The steam loco classes made sense up to a point. A = 4 driving wheels, B =
6 driving wheels, etc. Number = cylinder diameter. Then it gets complicated.
>TGR kept almost in alphabetical order and derivatives had an A suffix (XA,
>VA, ZA). Road numbers began at 1 except derivatives and upgrades.
And imports.
As to silly class schemes, how about NSWGR pre-1924?
Cheers
David