Hi Simon,
I am guessing it was a colleague of yours (Jamie) who asked similar questions on
http://www.namepros.com/domain-appraisals/266112-london-co-uk.html just over a year ago. I think the advice here would be the same - either cash in or develop.
It depends on budgets and time open to which route to development is best , as it would be a shame to waste a couple of the better names ie. london, with a poor website.
Cheers,
Rob.