Wow, what a flurry of excitement! It's such an interesting topic, and by a bizarre twist I've spent the last week or two researching Rudges in the late 1930s ISDTs. The speedtracktales website is brilliant. I love the detail, particularly the "final reports" that provide information that would be extremely difficult or impossible to glean ten years ago.
A word of caution about "ISDT survivors". I'm sure there are some genuine survivors, but there are also fakes. There's a particularly nice "1937 ISDT Rudge" (VSL869) out there, owned by a member of the REC executive, which is no such thing. Despite the owner regularly calling it "my ISDT", a photo of it on the REC web page labelled "1937 ISDT Ulster", and Rudge expert Bryan Reynolds describing it in his book "Rudge-Whitworth - The Complete Story" (where there are no fewer than three photos of it!) as "one of the 1937 factory ISDT machines", there is not a single part of it that went around in the ISDT!!! But it's very nice to look at, and that's what seems to matter these days. Such is the parlous state of motorcycling history...
Stew - good luck with your research. Some of the Rudge ISDT riders rode their own machines, and were entered under their own names. However even on the occasions where there was a team of bikes entered by Rudge Whitworth Ltd at least some of the riders had ownership of their machines after the event. I guess it depended on the "arrangements" between the riders and the factory. Note that riders could be entered under a number of banners: one rider could be part of an Official British team (say the British A Team in the International Silver Vase), AND a member of a Club team, AND a member of a manufacturer's team. As you can see from the Final Reports, there were awards in different areas.
Was it usually Leslie Ridgway, or Les?
Cheers
Leon