In message 201204270836042167-ken@nothereuk, at 08:36:04 on Fri, 27
Apr 2012, Bearded remarked:
But as part of the deal, minicabs should be much more visibly labelled.
I'm not suggesting the absurd 'must be yellow and white" Bournemouth
rules, but something much more visible on front back and sides than the
current disc. [How about decals on front, back and sides – safer for
customers, as well.]

Most of the minicab jurisdictions I'm familiar with have special
additional plates, here's an example:

http://www.cambridge.gov.uk/public/p...-plate-265.jpg

Sometimes it's front and rear, but possibly sometimes rear only.
Cambridge's rules also include:

"[the vehicle] must bear a company door signs showing ‘private hire -
pre booked only’."
--
Roland Perry