It's definitely that time of year. Heatbuster ads have been on the tubes for at least 6 weeks and those announcements about carrying a bottle of water with you (too late once you're in the bowels of the platforms) are resonating blandly on a regular basis. So, it's time for TfL's latest wheeze to cool the Underground down. Cue: GIANT FANS! Genius. Around 40 portable industrial fans will be introduced at key stations to......