Hi Richard,
I also had a quick chat with the owner at Corowa. After he told me of the 65mph on the road, I think he must have dispensed with the No-Spin diff fitted to Stalwarts and gone for a conventional type as in the Saracen. Reason I think this is that driving a Stalwart at 30 mph, they tend to lurch one way then the other due to the No-Spin diff action, so holding it on the road at 65 would be a nightmare. Would love to have tried it for comparison.
A good variation of British vehicles at Corowa, and a few surprise ones appearing at the last minute, the Stalwart included.