On the hottest day of the year so far I had a shoot at 1pm today in central London, thankfully in a cool office building and with not too much equipment to carry around, but that didn't take too long so I escaped underground to my (favourite) station, where the temperature was lower than at street level.  While I waited for my air-conditioned Circle Line train to arrive I had time to experiment some more with long exposures.  Ironically the tube and overground networks were both subject to speed restrictions today because of the heat.  I'm not complaining.