From scot-rail.co.uk:
"The Class 320's began receiving overhauls at Doncaster Wabtec in February 2011. The first unit, 320314 was moved by GBRf under it's own power between Shields Depot and Doncaster via the ECML, and took just over 4 months to complete".
Sunday was the 15th, and #320313 supposedly left on Friday 13th [may have been delayed].
Unit Number Arrived Doncaster Wabtec Departed Doncaster Wabtec
320314 14/02/11 06/06/11
320315 26/05/11 02/08/11
320306 03/08/11 21/09/11
320302 24/09/11 08/11/11
320304 08/11/11 15/12/11
320318 15/12/11 30/01/12
320303 30/01/12 06/03/12
320313 07/03/03 13/04/12
320308 14/04/12 Estimated 21/05/12