In response to the the OP, it seems plain to me on structural grounds that the more viscous topping must go on first. When you have the good fortune to have clotted cream that goes on first and the jam on top. But when you are being served whipped cream as a substitute it is practically necessary to spread the jam first and than spoon a bit of structurally-unsound whipped cream on top of it. 
When you lack clotted cream and jam, scones can be eaten with butter and Vegemite®.