in the 80's I had 2 or 3 fail on the XD. im sure this might have had to do with putting 30/3 globes in instead of the 20/5 globes, but they failed.

Relays solved the problem - and reduced the internal heating of the switch as well.

Snap - the sedans (X and E Series) had 4 brake lights - 80w normally (6.5a) and a trailer added another 3.5 or so. The XF Ghia's got 2 brake light switches in series and in them the break was usually in the Lamp Test panel where the complex thick module which tested the break light drop usually failed carrying the load when you plugged a trailer in.

We noted that putting a relay in fixed the problem for a longer term then. Thats all.

Nigel

Nah, you're right - I forgot the extra power of the trailer lights.
Just posting my experiences of normal running with 3 x 21w lights.

And I'm a big fan of relays also.