Its not a traditional keyway - the crank has a flat on it and there is a corresponding one inside the pulley. It is the difference between these two D shapes that causes the play.
The oil pump is also driven by two flats on the crank.
That why I don't remember a key then:) I might have to go examine the spare crank now.
Not sure why I didn't see play - its an ex-Freelander engine I re-purposed.
Strangely, had a work conversation about keys this afternoon - seems we might not employ "fitters" anymore - complaints about having to "fit" long keys in the main shafts of one of our products - and now machine shop complaining about being given them to machine down - which now we know, probably explains some other issues we couldn't work out once the machine is in production the other side of the world!
A common problem I've found when rebuilding engines is where the corrosion has caused the pulley to seize solid onto the end of the crank. It's a real pain because the pulley seems to consist of solid body with flimsy flange tacked onto the back - you can't use any force to prise the pulley pulley forwards without bending the flange. If yours had seized onto the crank like this, you wouldn't have noticed any play. If you actually removed the pulley - ignore!
SV VVC 170 - 170.4 bhp @ 7100 rpm - 142.4 ft.lb. @ 4900 rpm