fleet as they run beside the sea. After repair at Derby Litchurch Lane Works, 357203 was repainted and re-entered service on 30 July 2009. Similar work was carried out on the rest of the fleet over the next 21 months at Bombardier's Ilford Depot, where the units were repainted into their original white colour, but with dark blue doors, and branded with both "national express" and "c2c" logos in lower-case. The "Quiet Zone" stickers are now white with sky-blue lettering instead of magenta with white lettering. c2c ran a special "Farewell to the Blue Train" railtour service to commemorate the last day of running in passenger service of the blue livery on Saturday 5 March 2011. Regenerative braking On 9 November 2006, unit 357028 was sent to the Velim railway test circuit in the Czech Republic for safety testing to obtain certification for a regenerative braking system which had been trialled for many months on the Class 357 fleet. In March 2007, 357028 returned from the Czech Republic, having gained safety certification, and c2c began fitting the regenerative braking systems to the rest of its Class 357 fleet, becoming the first UK train operator to do so. On 3 June 2007, the eve of World Environment Day, unit 357010 was given an all-over green vinyl sticker livery with magenta doors and the tagline: "All c2c trains are greener now – find out more at – www.c2c-online.co.uk – c2c – the greener way to go" to highlight the completion of the scheme, which has given energy savings of up to 21%. 357010 lost its green livery in March 2011 as part of the fleet's corrosion repair and repainting project. Operations The two fleets of units are used interchangeably on all c2c services on the London, Tilbury and Southend line. Trains are generally formed of a single unit (4 cars) or two units (8 cars) working in multiple during off-peak times, and strengthened to two or three units (12 cars) during the morning and evening peak times. 71 of the 74 units are required to run the current normal timetable. Five units were loaned to sister National Express operator National Express East Anglia (then branded 'one' Railway) for a period ending in 2006 to accommodate the transfer of three Class 321/3 units to Silverlink (themselves to cover for Class 321/4 units hired to Central Trains). The units were generally used on London