of the design had begun in 2007, with an investment of about £45 million.

In September 2009, Alstom unveiled the X'trapolis UK, unusually an articulated vehicle, using 15.6 m cars, with individual carriages proposed to be supported at one end by a bogie and at the opposite end by a linkage to the next carriage. The shorter vehicle allowed a slightly wider design; the smaller number of bogies was to have resulted in a train approximately 40 tonnes