Ok Nev I've installed the Brooklands track from the link given earlier in the thread.
It shows up in the sim as Brooklands 1937. The readme calls it V1.5 by BigBen.
I used the largest of the tracks, The Outer.
I found the Voiturette class was ok. Tryed up to 20 cars with no problems.
With the bigger cars not so good. They never seem to get round the first tight corner onto the main track with out a horrendous crash. At that point I had lockups on 2 occations. Didn't have to reboot, used Ctrl Alt Del & shut it down from the task manager.
Once they sorted themselves out from the crash they seemed to go ok from there on.
I found if you reduce the number of cars down to 10 they are better behaved.
Also tryed the 1928 Mercedes SSK mod on the same track. Only 10 cars total in the mod so no problems there.