The first unit departed Adtranz's Derby works in April 1999 to Chart Leacon for testing and mileage accumulation as part of the lengthy Railtrack Safety Case procedure. Construction of the remainder of the order began in January 2000. The cars are supplied in overall white livery, Connex/South Eastern Trains colours and brandings being applied with vinyl overlays. Maintenance of the SET 375 fleet is at Chart Leacon as a SET/Bombardier joint venture. Introduction to service of the class has been slow whilst de-bugging takes place and the contractual reliability targets achieved, however full introduction to service which would allow major service improvements is impeded until the power supply systems are upgraded. There were initial difficulties with coupling and uncoupling en route which resulted in services being recast to avoid the need for this operation. A further problem occurred in January 2004 due to problems with the cab doors and this resulted in a temporary withdrawal of all SET Electrostar units.

375604 a 4-car unit member of class 375/6 showing Driving Motor Second N° 67804 & Pantograph Trailer Second N° 74204 while still in undercoat at Ramsgate depot on Thursday, 21 September 2000.

The lowered pantograph on PTS 74204.

A possible future configuration which is being considered is a five car variant by adding another MS to a four car formation. In August 2003 this was trialled with a temporary reformation of 375604 containing additional car 74253 (from 375603) marshalled next to motor coach 67804. 5 car unit testing was completed in September of that year. All SET Electrostars had selective door opening enabled in August 2003.

375s will later this year (2004) be fitted with dedicated 1st Class sections in the 12 seats behind each driving cab. This will mean that on a 12 car train formed from 4 car units there will be 6 sections of 1st Class, four of which will have to be open so people can move through the train.

photograph by Paul Ferbrache

photograph by Paul Ferbrache