Just as a follow up, I did a search in York University library, and found a reference to John Vevers who described a "travelling chaise without horses"
John was 100 years after the so called Lord Vevers, but was describing a fundamentally similar device to the Reisewagen. Still this was 1769, and well before conventional references on cycle development. It appears that there were a number of these devices around at the time.
John Vevers was master of Rygate Boarding School in Surrey, and so could have been an offshoot of the Potterton lot who went to Hereford and to Richmond in Surrey