Short answer: It looks like you’re referring to the BR Class 37 locomotive, a diesel-electric British Railways Type 3 built in the early 1960s, with many examples still visible on preserved lines and heritage railways today. Context and key details

• What it is: The BR Class 37 is a diesel-electric locomotive (English Electric Type 3) built for British Railways as part of the 1950s–60s modernization. It earned the nickname “tractor” among enthusiasts for its distinctive sound and power delivery.

• Production and designation: Built starting in 1960–1962, with numbering in multiple series (e.g., D6600–D6999 and later TOPS numbers). The class was designed for mixed-traffic duties, including passenger and freight work.

• Performance and use: Early on, Class 37s powered mainline services in various regions and remained in active service for decades, including freight and maintenance roles; many have been preserved or still operate on heritage lines today.

• Notable examples and current status: A number of units survive in preservation or are active on heritage railways, and some privately owned examples periodically run or participate in special events. Specific units (like 37 075 and various preserved machines) illustrate the range of life histories for the class.

If you had a particular focus, I can tailor the details:

• Historical background and development
• Technical specifications (engine, power, weight, speed)
• Notable members of the class
• Preservation status and where to see Class 37s today
• Model and scale representations or collecting tips

Would you like a concise spec sheet, a brief history timeline, or a list of currently active preserved locomotives? If you can share a location or a specific unit number, I can provide targeted information.