English: Roundhouse, Barrow Hill These three British locomotives are quite unique from one another. The locomotive on the left is a Class 45/1 diesel locomotive. It is the only one of the three that has the 1Co-Co1 wheel arrangement and it differs from earlier members of the Class 45s by having electric train heating.

The Class 73 in the centre is a 600hp/1600hp electro/diesel and capable of running by either means. It can be driven electrically by picking up power from a third-rail. This brings me to make this point, that none of these locomotives are directly driven by their diesel engine. Even though the Class 45 has a 2,500hp diesel, (not massive by today's standard) it does not directly drive the wheels. Instead, the diesel engine powers a generator, which produces electrical current, which in turn powers electric motors that propel shafts to turn the wheels. Amongst other duties, Class 73s could always be seen on the Gatwick Express.

The Class 20 1000hp diesel locomotive, on the right, differs from the other two by only having one cab at the end of a rather long bonnet. The Class 20s usually ran in pairs and bonnet to bonnet. Of the three, the 20s were mostly confined to freight duties. They could, however, be seen hauling trains on rail-enthusiast specials, some of which went to Skegness.