One wheel is mounted flush with the axle end:
The other end shows the excess portion needing to be sawn-off:
Easy job with a piercing saw.
In this photo, you can see that I have test-quartered the wheels, with the offside (r/h) crank leading:
For those who don't deal with steam, that basically means that when the engine moves forward, it's the right-hand crank that will come round first, followed 90 degrees later by the nearside (l/h) crank.
I don't know yet whether right-hand lead is correct for the "S"-class. There were some British steam classes (I think the LNWR "G2A" 0-8-0 was an example) which had a left-hand crank lead, as does the Drewry "04" diesel shunter.