The London Mayor decided to deal with the issue of illegal minicabs by regulating and legalising them.

Details are at http://www.tfl.gov.uk/pco/ and still forbid touting for business on the streets, but do regularise the industry to some extent.

That said, I'd never take one off the street, and I certainly wouldn't recommend a single woman takes one.

Regular taxi fares (aka black cabs) have been adjusted several times since the Mayor came to power - first they went up significantly in the evenings, which meant that cab drivers earned enough in the early evening so they didn't have to work late nights; the evening rates have now been reduced again to persuade drivers to work later.