@techfashion...should you decide to go with a private car service, I can personally vouch for Blackberry Cars. We have never used them for an actual transfer to/from the ship, but any time we are in London we use them for transfer to our hotel from LHR and any place we want to go within London. They are VERY professional and reliable. They're not the cheapest...but you'll enjoy the feeling of "special" that they endow!