Bob, I found your post about your Isetta's original registration number very interesting. I am sure it is not news to you that registration number codes from the 'CD' series had been allocated to the Brighton area from March 1960 onwards. But here the plot thickens. You said that this Isetta was first registered in Newcastle-upon-Tyne. So why the Brighton number? Was it perhaps a special car that was used for other purposes initially? Of course it is well known that many Isettas, especially the later ones, spent some time in a dealer's showroom before they were first registered, but not usually with a Brighton number.
The other interesting fact is the low number of that registration. I am aware of several road test cars and press cars with 'CD' numbers, but they all had four figures (3288 CD = 1960 road test car, 3738 CD = 1961 advert car, 9107 CD = press car). I know of a few other Isettas with 'CD' registrations which, presumably, just happened to be registered in Brighton, but again they all have two letters and four numbers. Is yours perhaps an Isetta with a very special history?