All I know was that it was built as an experiment. I would guess that it might be something to do with distributing the weight differently as I understand the coal and water capacities were the same. I remember seing a photo of it in my late teens and thought I must have one to go behing my Triang Hornby Hall.
My attempt to conbvert the triang tender only ended in tears with my Hall eventually ending up with a Mainline 3500gal tender!
More recently and as I happend to have some spare tender chassis I had thought of doing a cut and shut using two chassis only to find there was so many differences I thought I'd 3D print the frames and use the wheel, but even then I was thwarted as the six wheeled tenders use 4 foot something wheels while this one uses 3'8.
Thanks for the compliment, I'll probably put it behind a castlke. I've got a couple of duplicates so this will add something a little different.