The Tube's first air-conditioned train has started running - on a stretch of line entirely in the open air.

And although the new, cool trains will serve 40% of the Underground network over the next few years, there are no immediate plans for air-conditioned trains on the deep-lying, often boiling hot lines such as the Bakerloo, Northern and Piccadilly.

London Mayor Boris Johnson joined passengers on the first of the new trains on Monday which will run, to start with, on the Metropolitan line from Wembley Park to Watford.

The new trains feature:

  • Air conditioning
  • Walk-through carriages
  • Wheelchair areas
  • Wider doors and walkways
  • Easier access between train and platform
  • Better audio and visual information systems
  • CCTV
  • An energy efficient braking system