BR Mark 3a Tourist Second/Standard Open (TSO) № 12049 was built in 1975/1976 by British Rail Engineering Ltd. (BREL) at Derby Litchurch Lane Works, for services on the West Coast Mainline (WCML).

The Mark 3a locomotive hauled coaching stock was constructed alongside the production line for the High Speed Train (HST) / Inter-City 125 Mark 3 coaches.

The Mark 3 coaches used a common bodyshell for all variants. This was the first time BR had used this philosophy in their coach designs.

The bogies fitted underneath a Mk3a coach are known as BT10 bogies. This design was a BR in-house design which is notable for the first use of an air spring for the secondary suspension.

BR and Virgin West Coast / Virgin Trains utilised the Mark 3a coaches on the WCML until the introduction of the Class 390 Pendolino units from 2002-2005.
After use with Virgin trains ceased TSO 12049 was transferred to work out of London Liverpool Street to Norwich for the ONE franchise.

In 2014 Greater Anglia announced an internal refurbishment program for its coaches, in addition to its ongoing repaint program. The refurbishment program ran from late 2014 until 2016. The main changes were:

• plug points
• new LED lighting
• new carpets
• new tables
• new seat covers
• upgraded environmentally-friendly controlled emission toilets with new floors and new taps
• re-painting of the carriage interior saloon and vestibule panels, walls and ceiling

The work was carried out by Vossloh Kiepe in a specially prepared area of Abellio Greater Anglia’s Crown Point Depot in Norwich.

TSO 12049 continued its service on the Great Eastern Mainline (GEML) until the 24th of March 2020 when, due to changes in the regulations for access for persons of restricted mobility, Greater Anglia returned the vehicle  to its owner, a Rolling Stock Company (ROSCO) called Porterbrook. The last locomotive hauled service by Greater Anglia ran on the 24th of March 2020.

The livery history of TSO 12049 reflects the various BR operating structures and the franchise operators who have utilised the coach:-

• BR Corporate Blue/Grey livery
• Inter-City Executive livery – also known as Raspberry Ripple livery
• INTERCITY Swallow livery
• Virgin West Coast / Virgin Trains branded red & grey livery
• Debranded Virgin West Coast / Virgin Trains red & grey livery
• ONE ‘refresher’ livery
• Debranded ONE livery with interim National Express brand comprising a white waist height stripe with company lettering
• Debranded ONE livery with a white waist height stripe with ‘Abellio Greater Anglia’ and ‘Greater Anglia’ branding
• Greater Anglia livery (with & without Abellio branding)

The Northampton and Lamport Charitable Incorporated Organisation (NLRCIO) thank Porterbrook for the donation of this coach.