http://forums.autosp...rised-bath-tub/
which contains a link to the chapter and verse provided by Roger Lund in another thread:
The motorised bathtub was driven by Graham Hill for a "couple" of laps as a diversion between races at the '59 Boxing Day Brands meeting, his quickest lap being 2mns 59.7 secs. The car had been the subject of John Bolster's Yuletide Road test the previous week.
The no plate on the green TR behind the fence looks familiar, possibly a competition model, perhaps done as an Octane article in recent times; I cannot find the file.
Roger Lund