Sixteen three-car units were introduced in 2000 by Northern Spirit then operated by Arriva Trains Northern and now by Northern Rail on the Wharfedale and Airedale lines in the West Riding of Yorkshire, England (between Leeds, Bradford Forster Square, Ilkley and Skipton). They are based at the Neville Hill depot in Leeds and painted in the livery of West Yorkshire Metro, the local passenger transport executive. Due to increased passenger numbers, the sets were lengthened to four cars, 333001 - 333008 in 2002 and 333009 - 333016 in 2003 - this was funded by Metro and the Strategic Rail Authority. However, this funding ran out in 2007 and as a consequence of this the 4th carriages could have been removed. Had this happened the 4 car 321s would have been removed from Doncaster services on to W