Following the hasty abandonment of the 1955 pilot scheme, in which large orders were placed predominantly for Type 2 diesel locomotives of between 1,000 and 1,365 engine horsepower, BR recognized the need for a more powerful Type 3 of around 1,750hp, which saw the beginning of the diesel-hydraulic 'Hymek' era on the Western Region and the more successful EE Co machines. After operating experience, the response by the operating department to the Type 3’s Co-Co wheelbase, was unanimously favourable, particularly as the versatile locos had sufficient power to take on many duties performed by the cumbersome Type 4 1Co-Co1s in the 2,000hp power range. The Type 3 certainly knocked spots off the Type 2s in both power and its versatility. This view (below) of the Vulcan Foundry on August 2nd 1961, shows the first batch of Type 3 Co-Cos (numbered D6700-D6741 in the series) in various stages of construction.

As Below

Above,

After the flexible gangway connecting doors were abandoned from D6819 onwards, the nose end was completely revised with a new four panel route indicator panel centrally placed, and the air horns were relocated in the cab roof. In this pleasing shot, the EE Co’s official photographer has opted for a somewhat unusual viewpoint of the assembly line at the company’s Vulcan Works at Newton-le-Willows; it shows a batch of the final machines in various stages of construction in April 1964.

The EE Co's desire to standardize wherever possible meant that many components of the Type 3 superstructure and various other fitments were in common with the Type 4, and externally the D6700s differed very little from their earlier D200 cousins. Powered by the EE Co's 12-cylinder 12CSVT engine, the new Type 3 was essentially a scaled-down version (using a shortened bodyshell) of the D200s introduced on the Eastern Region in 1957. Since the ER was familiar with the EE Co’s pedigree, the operating department was quick to employ the new mixed-traffic Type 3s on the Liverpool St-Cambridge-Kings Lynn passenger services.

Text copyright of David Hey