We arrived at Heathrow early in the morning and couldn't check in until late afternoon, so instead of dealing with luggage and wandering around ourselves, we arrange for a Black Taxi tour to pick us up at the airport, spend 3 hours touring and then drop us off at our accommodations near Gatwick airport, which we were flying out of the next day. They assigned a very nice tour guide/driver (Ray Winstone). Communication with him via WhatsApp was easy and effective. He was waiting at the airport as planned and we discussed options for the day. We had a very nice tour - getting the most out of the few hours we had and finishing with a visit to the Borough market for snacks (which I had specifically asked for). Ray was interesting, knowledgeable and pleasant. I would highly recommend him and Black Taxi Tours.