Kestrel

HS4000, named Kestrel, was a prototype high-powered mainline diesel locomotive built in 1967 by Brush Traction, Loughborough as a technology demonstrator for potential future British Rail and export orders. The locomotive number is a combination of the initials of Hawker Siddeley (the owners of Brush Traction) and the power rating of its Sulzer diesel engine (4000 HP).

It was of Co-Co wheel arrangement and was fitted with a Sulzer 16LVA24 engine rated at 4,000 horsepower (3,000 kW) providing a maximum speed of 110 mph (180 km/h) and weighed 133 tonnes. It was painted in a livery of yellow ochre with a broad chocolate-brown band around the lower bodyside separated by a thin white line running around the body.