BR Mark 3a Tourist Second / Standard Open Coach №12118 was originally built in 1975 / 1976 by British Rail Engineering Ltd. (BREL) at Derby Litchurch Lane Works, as locomotive hauled stock for the west Coast Mainline (WCML) alongside the Inter-City 125 Mark 3 coaches for the High Speed Train (HST).

The Mark 3 coach was the first BR coach design to share a common bodyshell between all variants.

The bogies fitted underneath a Mk3a TSO are known as BT10 bogies. This design was a BR in-house design and saw the first application of air springs in the secondary suspension.

After around thirty (30) years of service on the WCML with BR and Virgin West Coast / Virgin Trains, who carried on utilising the BR vehicles until the introduction of the Class 390 Pendolino units from 2002-2005, the coach 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 12118 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 12118 reflects the various BR operating structures and the franchise operators who have utilised the coach:-

• BR Blue/Grey Corporate 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’ branding
• Greater Anglia livery (with & without Abellio branding)