On the privatisation of British Rail's freight operations in 1996, English, Welsh and Scottish Railway (EWS), then a subsidiary of Wisconsin Central and since acquired by Canadian National, bought most of British Rail's freight operations. Many of the locomotives that EWS inherited were either at the end of their useful life or of doubtful reliability. EWS approached General Motors Electro-Motive Division (EMD), who offered their JT42CWR model developed from the Class 59. Initially classified as Class 61, this was subsequently given the "Class 66" designation in the British classification system. Two hundred and fifty were ordered and built in London, Ontario, Canada.
The Class 66 incorporated many ideas from North America and differed a lot from the Class 60, which had been recently built but to a more traditional layout.
Although unpopular with many rail enthusiasts, due to their ubiquity and having caused the displacement of several older types of (mostly) British built locomotives, their high reliability has helped rail freight to remain competitive.
The Class 66 design has also been introduced to 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. They currently operate on routes between Sweden and Denmark and between Germany, Belgium, The Netherlands and Poland. As a result of its well-known British identity, EMD Europe markets the locomotive as "Series 66".
Due to the similarity between the word 'class' and the Dutch boy's name 'Klaas', locomotives of this class are nicknamed Klaas or in plural Klazen.
Freightliner followed EWS by initially ordering five new Class 66/5 locomotives, and have continued to order in small batches. As of summer 2007, the 66/5 fleet had reached 93 examples, numbered 66501-520/522-594, with 66521 having been withdrawn, and later scrapped after the 2001 crash at Great Heck.
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. There are presently twenty-five examples of this class, numbered 66601-625.
During 2004 the company also took receipt of the most recent Class 66/9 sub-class of the locomotive, which are a low-emission variant. All new locomotives for all companies are now of the low-emission "T2" type. The original two such locomotives remain as 66951/52.
During April 2006, five additional locomotives (numbered 66718-722) were delivered. These are of the low-emission kind, similar to the 66/9s in service with Freightliner. The livery differs slightly from the original seventeen, using a lighter blue and 'Metronet' branding on the sides. Their primary use was to work infrastructure trains for Metronet, but now for Metronet's succesor Transport for London. A further order for five more locomotives (66723-727) was delivered in early 2007. These locomotives are painted in a new livery of pink, white and blue, which is similar to First Groups corporate livery. In April 2008 First GBRf took delivery of another five locomotives (66728 - 732). They are painted again in the corporate First Group livery, and 66728 is expected to be named on Friday 18th April 2008 at March West TMD
Direct Rail Services (DRS), a subsidiary of BNFL, is the latest company to opt for Class 66 locomotives. Previously, they had relied on a fleet of ageing second-hand Class 20, Class 33, Class 37 and Class 47 locomotives. In 2002, DRS ordered ten Class 66/4 locomotives from EMD. These were delivered in 2003, numbered 66401–410, and are employed on new Anglo-Scottish traffic, some with Stobart Rail. They are painted in a variation of DRS's blue livery. More locomotives have since been ordered, with ten (66411–420) delivered in 2006 and another ten (66421–430) delivered in late 2007. As of 2008, DRS had another four locomotives (66431–66434) on order.
|Subclass||No. built||No. range||Operators||Loco nos.||No. in traffic||Withdrawn / Remarks|
|66/3||5||66301-305||Fastline||66301, 66303, 66304||5||66302 and 66303 awaiting delivery|
|66/4||10||66401-410||DRS||66401-410||10||DRS are removing these ten from traffic, and returning them to their ROSCO shortly.|
|20||66411-430||DRS||66411-430||24||Low-emission locomotives. 4 on order for 2008 (66431-434).|
|66/5||81||66501-581||Freightliner||66501-520/522-581||80||66521 written off in the Great Heck rail crash.|
|66/9||2||66951-953||Freightliner||66951-953||3||Low-emission locomotives. 5 more on order for 2008 (66953-957).|