Only used at the beginning of my cycling life by others in London and SE England where it was often not far to the event and a lot of folk still didn't have cars in the late 60's/ early 70's.
I went looking for the Cyclo tub carriers in my collection and I can't find the steel ones in the chaos that is my shed at the moment!
I did find the alloy Cyclo ones tho and a pair made by Cliff Peters shop in Birmingham (obviously well used) which illustrates how easy it was to make your own.
Might have to start a separate 'Tub Carrier' thread soon
Richard