A couple of minutes Googling came up with this:
"It is a good idea to mount new tyres (or those with the least wear) in back instead of in front. The driver has little or no control over loss of rear wheel grip. By mounting new tyres in the back, grip is balanced between the two axles, which improves safety. Despite weak grip, the driver controls the front axle with the steering wheel, while the rear axle grip is optimised by the new tyres."
This obviously applies to all cars, not just Mk1 Leons
"It is a good idea to mount new tyres (or those with the least wear) in back instead of in front. The driver has little or no control over loss of rear wheel grip. By mounting new tyres in the back, grip is balanced between the two axles, which improves safety. Despite weak grip, the driver controls the front axle with the steering wheel, while the rear axle grip is optimised by the new tyres."
This obviously applies to all cars, not just Mk1 Leons