The Wales & West franchise (later Wessex Trains) originally operated twelve Class 158 Express Sprinter units on long-distance services on the Wessex Main Line.
These units were extended into three-coach formations with the acquisition of further units.
Unlike the purpose-built three-car Class 158s and Class 159 units, the centre car was a Driving Motor with the cab locked out of use and an adapter to connect the different-sized gangways.

In 2006, First Great Western (FGW) inherited the Wessex Trains fleet following the merger of the Great Western and Wessex franchises.
FGW then swapped most of their former Wessex Trains Class 158s for former First TransPennine Express examples.
This was so that FGW could have all Class 158 units that were owned by Porterbrook.
During late 2007 and early 2008, the FGW Class 158 Express Sprinter fleet was refurbished.
Improvements included: re-upholstery of seats, and repainting or replacement of interior fittings, alterations to interior lighting and total replacement of toilets.
Additionally, the windows have been replaced with safer laminated glass and Halon fire extinguishers replaced with foam ones.
At the same time, the units' engines were overhauled and the units repainted in FGW's own lilac and blue colours.


The fleet is now used on long-distance services between Exeter St Davids and Plymouth / Penzance, Cardiff Central and Taunton / Portsmouth Harbour and Great Malvern / Worcester Shrub Hill and Brighton / Weymouth.
They are now also used on the Tarka Line on services between Barnstaple and St James' Park replacing the class 143 pacers which were running on the line.
Great Western Railway operates a total of 18 units, of which 6 are hybrids (units where one end coach is a driving coach from another unit of the same class tagged on to a 2 car unit), one is a purpose-built 3 car unit and the remaining 11 are two coach sets.
The Wales & West franchise (later Wessex Trains) originally operated twelve Class 158 Express Sprinter units on long-distance services on the Wessex Main Line. These units were extended into three-coach formations with the acquisition of further units. Unlike the purpose-built three-car Class 158s and Class 159 units, the centre car was a Driving Motor with the cab locked out of use and an adapter to connect the different-sized gangways.
In 2006, First Great Western (FGW) inherited the Wessex Trains fleet following the merger of the Great Western and Wessex franchises. FGW then swapped most of their former Wessex Trains Class 158s for former First TransPennine Express examples. This was so that FGW could have all Class 158 units that were owned by Porterbrook. During late 2007 and early 2008, the FGW Class 158 Express Sprinter fleet was refurbished. Improvements included: re-upholstery of seats, and repainting or replacement of interior fittings, alterations to interior lighting and total replacement of toilets. Additionally, the windows have been replaced with safer laminated glass and Halon fire extinguishers replaced with foam ones. At the same time, the units' engines were overhauled and the units repainted in FGW's own lilac and blue colours.

The fleet is now used on long-distance services between Exeter St Davids and Plymouth / Penzance, Cardiff Central and Taunton / Portsmouth Harbour and Great Malvern / Worcester Shrub Hill and Brighton / Weymouth. They are now also used on the Tarka Line on services between Barnstaple and St James' Park replacing the class 143 pacers which were running on the line. Great Western Railway operates a total of 18 units, of which 6 are hybrids (units where one end coach is a driving coach from another unit of the same class tagged on to a 2 car unit), one is a purpose-built 3 car unit and the remaining 11 are two coach sets.
British Rail Class 158