[2] To enable it to offer its stated lower pricing to customers, EWS needed to reduce operating costs and increase availability.

[2] After reviewing the existing privately commissioned Class 59, which was more powerful, highly reliable and with lower operating costs, EWS approached its builder Electro-Motive Diesel (EMD), then a division of General Motors.

[12] The Class 66 design has also been introduced to Continental Europe where it is currently certified for operations in Germany, the Netherlands, Belgium, Luxembourg, Sweden, Norway, Denmark, France, and Poland, with certification pending in the Czech Republic and Italy.

By 2011, following an increase in UK rail traffic after the 2008 Global Economic Crisis, EMD were struggling to source critical components of the locomotive — specifically castings.

The final units of the Class 66 were produced in the London, Ontario plant that year following an industrial dispute and the introduction of new EU crash and emissions regulations which culminated in the cessation of production.

Due to a reduction in European freight volumes and migration of several operators to electric traction using multi-current locomotives such as the Alstom_Traxx and Siemens Eurosprinter, since mid-2012, a number of EMD Series 66 locomotives have been imported by UK rail freight operators and converted to UK type specifications.

The presence of these power units in the UK circumvented European emission compliance regulations and permitted them to be exported to EMD Muncie for installation in further class 66 bodyshells.

Stage 3b would have required additional exhaust treatment equipment that could not easily be accommodated within the UK loading gauge.

On these specific locomotives, the knuckle coupler has been modified to allow remote releasing from inside the cab, whilst in motion.

[17] It also includes fifteen locomotives fitted with RETB signalling equipment, for working in northern Scotland and RETB-fitted branchlines.

In 2000 a new Class 66/6 sub-class was built, with a lower gear ratio, enabling heavier trains to be hauled, albeit at slower speed.

[18] In June 2012, 66734 derailed at Loch Treig whilst working 6S45 North Blyth–Fort William and was consequently cut up on site and scrapped.

[19] The final seven Class 66s to be built for the British market arrived on 12 February 2016 aboard the cargo ship Happy Dragon at Newport docks and consisted of numbers 66773–779.

[citation needed] 66779 remained under a tarpaulin until 10 May 2016 when it was revealed at the NRM York with a special livery and nameplates to commemorate the fact it is the final Class 66 ever built for the British market.

It was unveiled in a special ceremony inside the Great Hall at the National Railway Museum in York on 10 May 2016 before staying there opposite its namesake, No.

Fastline operated intermodal services between Doncaster and Birmingham International Railfreight Terminal (BIFT), and Thamesport, in North Kent, using refurbished Class 56 locomotives.

The British train drivers' union ASLEF has complained that the locomotives are unfit and unsafe to work in, citing excessive heat, noise levels and poor seating.

Research showed that in July 2006, when the weather had been extremely hot, the number of incidents where a driver had passed a signal at danger (SPAD) increased.

[27] EWS entered into discussions and made amendments to a series of trial locomotives,[27] GB Railfreight and Freightliner also investigated cab improvements.

[29] In Norway, CargoNet related complaints about the noise levels in the CD66 variant of the Class 66 resulted in higher pay rates for drivers.

[citation needed] In 2006, Hornby Railways launched its first version of the BR Class 66 in OO gauge range in a variety of liveries.