Jam first.
Cream gets dolloped on after with a teaspoon.
Can't believe there are folks that would suggest otherwise. How the hell do you get jam to spread out on top of the cream – unless you're some sort of skinny latte freak who doesn't put enough cream on.
By estimate rather than measuremetn (that would be too anal…), you should be looking at quarter to half inch of jam, with a good inch of cream on top. I'd challenge anyone to get the jam to spread over anything like an acceptable amount of cream.
I guess they must be tight in Devon – the phrase used by my old Cornish farming relatives comes to mind "tight as a duck's arse"
… and yes – Golden Syrup is loverly with clotted cream on top