The Class 20 is perhaps one of the oldest diesel locomotives that still sees revenue earning work on the UK network. A simple design, but one that came to symbolise the transition from steam to diesel traction during the late 1950’s and early 60’s, with these flexible and versatile locomotives finding their way into all walks of life.
The roots of the Class 20 can largely be owed to many of the early diesel locomotive designs of the 1950’s. As part of the Rail Modernisation Plan of 1955, an entire slew of diesel alternatives were constructed to try and replace the now very tired fleet of steam locomotives that were the backbone of the UK railway network.
The Class 20 was among the most basic designs of this period, weighing 73 tonnes, producing 1,000hp from its English Electric 8 SVT engine, and with a top speed of a
reasonable 75 mph. The general principles of the locomotive were done to allow it to work anywhere steam engines were able to, ranging from small backwater branch lines to heavy mainline work. The general purpose of these engines was primarily for freight, and thus, unlike locomotives which were designed to operate passenger trains, the locomotives were not fitted with train-heating, be it through Electric Train Heating (ETH), or steam heating boilers like on the Class 40.
When the initial batch of locomotives were unveiled in 1957, these were built with flat front headcode discs, similar to that of the steam locomotives they were replacing. The disc system was replaced in 1960 by physical headcodes displayed inside boxes, and thus locomotives built after D8127 (the 127th locomotive) were fitted with square headcode boxes at either end. Perhaps the most interesting design note of the 20 is the fact that it only has a cab at one end, similar to the American GP7 and GP9. This caused early issues due to lack of visibility when operating nose first, though, in essence, it has no difference to the view a driver of a steam engine would experience with the boiler obscuring the view. The usual configuration of Class 20’s in operation was to have them work in pairs, with cabs positioned at opposite ends for ease of use.
Class 20’s first made an appearance in London, being based at Devons Road depot, and put to use on transfer freights across the capital. As production of these engines continued, they were allocated much further afield, starting with the Highlands of Scotland, where they operated on the tightly curved branches to the Kyle of Lochalsh, Inverness, Wick and Thurso, as well as on the mainlines via Hawick, Ardrossan and Dumfries.
Almost immediately, the class gained a reputation for sturdy reliability and ease of use, due largely to the fact that the engines were impressively basic in their design. Other
early diesels were either far too complex for regular use, or were so poorly built they were unreliable, but the Class 20’s easily proved their worth, and very soon the likes of early freight steam engines were relegated to the scrapyard in the wake of the 20’s arrival.
Such was the success of these engines, the initial order for 128 locomotives was doubled, and after the initial production run ended in 1962, engine building was restarted in 1964, with the first of the new batch being delivered in 1966. Locomotives were regularly put on coal trains, with some engines retrofitted to make them compatible with the new electronically controlled Merry-Go-Round system (MGR), complete with new hopper wagons to replace mineral wagons that dated back to the early 20th century. Production of Class 20’s would eventually end in 1968, with 228 engines delivered, making it among the most numerous class of locomotive to operate in the UK.
The Class 20’s did find their way onto passenger services, but not frequently. The first use of 20’s on passenger trains was to haul empty carriage stock out of Norwich station, but eventually a small batch were fitted with steam heating pipes to work with Class 37’s on passenger trains in the Scottish Highlands. Other than that, Class 20 haulage is a rarity, usually reserved for railtours and, in the past, relief trains in
the summer to seaside resorts such as Skegness and Great Yarmouth.
Class 20’s worked solidly from the 1960’s well into the 1990’s, and their fleet remained strong with British Rail until the advent of locomotives such as the Class 60 in 1991. With the appearance of the 60’s, many Class 20’s were pensioned off their coal workings, but could still find a home hauling engineers trains. A small fleet of Class 20’s even found their way into the Channel Tunnel, working alongside SNCF shunters as part of the track-laying process when the tunnel was being built in the early 1990’s.
By the end of the 1990’s however, Class 20’s were continuing to fall in numbers. Scrapyards up and down the country were strewn with rusting husks, the fleet gradually being withdrawn as the 40 year old design began to look its age.
However, this wasn’t the end for the 20’s, and, even today, these versatile engines continue to earn their keep for a variety of operators. Perhaps the most notable operator of the Class 20 following privatisation in 1994 is Direct Rail Services or DRS, formerly a division of British Nuclear Fuels. Class 20’s were, and still are, employed on working nuclear flask trains across the UK, with locomotives in their fleet
modified with up-to-date light clusters. Today, DRS operates 8 of these locomotives, though their intention is to replace them with the arrival of the new Class 68’s and 88’s.
Aside from DRS, Class 20’s were employed in the construction of High Speed One in the early 2000’s, while another set of locomotives were put to work delivering brand new London Underground S-Stock from the Bombardier factory at Derby Litchurch Lane to Neasden in London. The Harry Needle Railroad Company (HNRC) also employs a set of 20’s for occasional lease when required.
The Class 20’s have also made some very distinctive runs. Between September 17th and September 25th, 1999, Class 20’s numbers 20901, 902 and 903 hauled the Kosovo Train for Life from Kensington Olympia station in west London to Pristina station Kosovo via Prague, hauling with them 800 tonnes of aid for the population of the besieged region. Another Class 20, 20188, a preserved locomotive on the Nene Valley Railway, was dressed up to look like a Soviet armoured train for the 1995 James Bond film Goldeneye, though its appearance was somewhat brief and it smashed
into a rather fake looking tank outside Wansford station.
Today, 22 locomotives have been preserved across the country, including class premier D8000, which is owned by the National Railway Museum at York.
Overall, the Class 20’s have proven themselves time and again to be a sturdy and reliable set of locomotives that brought about the end of steam traction on majority of freight workings across the UK. While their numbers now dwindle after 60 years of operation, the locomotives are still the pride of many operators, be they the humble preserved railway, or the busy mainline operator.