Red "Velo City" recumbent (with aero shell) turning left out of Grosvenor Crescent onto Palmerston Place. Think I saw a photo of this on a thread here previously.
Made me smile and added to my already good mood as I shot my way past all of the stationary traffic in the West End snarl-up this evening.
*edit* Did some searching; it was a Quest Velomobile and is actually a trike! Previously seen on Laidback's photo stream for the Festival of Cycling tour.