Since we unveiled our line up of 37/4s in classic BR era condition and liveries,  there has been much call to know what the other part of our Class 37 run 3 line up would look like?

Of course, while it's easy to shout "duplication" because we did a Class 37, it did miss the point that we pride ourselves on; we did the variants that had never been done before. Okay, so the original Class 37/4s were done before, but market demands dictated that we go there. The calls for us to do them were huge, so we obliged. 

However, the other side of this run is us sticking true to our principles of breaking new Class 37 ground, and we go somewhere that no manufacturer has been before; The Mirrlees powered Class 37/9s!

History

Introduced in 1986-7, the repowered Class 37/9s were an off-shoot of the ill-fated ‘Class 38’ project, a proposed 1,800-2,250hp Class 31/33/37 replacement with the haulage capability of a Class 56 or 58. As many as 500 units were planned, which attracted significant interest from locomotive builders and engine manufacturers from the UK, Europe and the USA. Two British manufacturers quickly established themselves among the front runners with engine designs that boasted incredible fuel efficiency.

The Mirrlees Blackstone MB275T from Hawker Siddeley and the Ruston RK270T from GEC Transportation, could both develop over 2,000hp from a straight six cylinder layout, providing a significant reduction in maintenance costs. Having both passed BR’s punishing approval process, a further further two-year trial was undertaken using six Class 37 donors that were undergoing ‘refurbishment’ at BREL Crewe Works. As the Mirrlees unit was slightly heavier than the English Electric 12CSVT they were replacing, they were included in the 120-tonne ballasted group, otherwise known as ‘heavyweights’.

Hawker Siddeley offered four engines for Nos. 37901-4 and these were mated to a Brush BA1005A alternator, while the Ruston in Nos. 37905/6 was partnered with GEC G546AZ electrical equipment. Both engines were set to deliver just 1,800hp to avoid overloading the existing EE traction motors. There were external modifications too. The Mirrlees unit with silencer was longer and taller than unit it replaced, resulting in a new ‘peaked’ roof, while the Ruston, which tipped the scales at just 13.75 tons, also featured a revised roof to accommodate a new silencer layout.

The first pair, Nos. 37901/2 (ex-37150 and 37148), left Crewe at the end of October 1986, while the two Rustons (ex-37136 and 37206) were completed by mid-December. Nos. 37903 (ex-37249) and 37904 (ex-37125) followed in February and April 1987 respectively. Cardiff Canton was chosen to look after the small fleet and these were allocated to the Metals sub-sector for local steel operations, although they were also fitted with slow-speed control for coal duties. All were delivered in Railfreight grey, with No. 37901 quickly being named Mirrlees Pioneer and No. 37905 Vulcan Enterprise.

The Class 37/9s quickly found their feet, despite being intensively diagrammed, and working in pairs had no problem taking over from the double-headed Class 56s on the 3,060-tonne Port Talbot-Llanwern iron ore trains. However, they were found to load much more slowly leading to the ‘slug’ nickname for the class. Their reliability was also impressive, although some issues were experienced with both the turbochargers and the silencer configurations on both designs. The latter resulted in both types receiving modified roof layouts.

Unfortunately, the ‘Class 38’ project was cancelled in December 1987. Despite this setback, BR chose to purchase the engines rather than return them to standard condition. Happily, the incredible fuel efficiency and extended maintenance periodicity displayed by the Mirrlees design likely contributed to Brush winning the Class 60 contract in 1988, and this was specified with the eight-cylinder version of the power unit.

By August 1988, Nos. 37903/6 had both been outshopped in the new triple-grey Metals scheme, with Nos. 37904/5 being similarly repainted in 1990 and Nos. 37901/2 in March 1991, by which point the fleet was beginning to wander much further afield. However, it wasn’t long before their non-standard nature began to count against them and nearly all spent periods in store during the 1990s. While all six passed to Trainload Freight South West / Transrail in 1994, with Nos. 37901/6 also receiving big ‘T’ logos, No. 37904 was the first to be permanently stopped at Canton in April 1996.

The resurgence of freight in the early EWS era saw regular work return for the remaining quintet, but with Class 66s starting to arrive the inevitable was held off only until November and December 1998 when Nos. 37901 and 37903/5 were also sidelined. The final pair, Nos. 37902/6, were switched off in January 1999, although unofficially named No. 37906 Star of the East was reprieved as part of the EWS ‘heritage fleet’ for galas and open days and was even repainted back into Railfreight grey ahead of the Old Oak Common open day in August 2000.

No. 37903 was scrapped at Crewe Diesel in October 2005, while No. 37904 suffered the same fate at CF Booth, Rotherham, in November 2004. No. 37902 was acquired by Direct Rail Services in 2002, which then disposed of it to Sims Metals, Beeston, in April 2005 after cancelling its overhaul. Happily, No. 37901 was saved in 2003 and was a regular performer in preservation before being acquired by Colas Rail and then Europhoenix in 2016 and gaining the operator’s house colours. It subsequently returned to main line operations in 2022 for the EP Rail ‘spot hire’ subsidiary and was recently repainted back into Railfreight Metals livery. The two Ruston locos also both worked in preservation at various points over the last 20 years, although they are now owned by UK Rail Leasing and are undergoing a slow return back to operational, albeit non main line, condition.

WATCH: Learn The History And Take A Closer Look At The Model With Senior Project Manager Gareth Bayer

The Model

The first release of the Accurascale Class 37/9 covers three of the Mirrlees examples over the full life of the sub class, from original conversion, through their classic late sectorisation period right through to the present day. Let's look at the three locomotives on offer.

37901 Mirrlees Pioneer

When the six-cylinder Mirrlees Blackstone MB275T power unit was first lowered into carbody of the former 37150 it is unlikely that anyone involved in the re-engineering project envisioned it would still be working 38 years later, especially as the Class 38 project for which the engines were intended would be cancelled only a few months later. Built as D6850 in 1963 and already 23 years old when it was plucked from obscurity to become 37901, the doyen of the Class 37/9s, the conversion at BREL Crewe Works was completed in October 1986. Finished in Railfreight grey and quickly named Mirrlees Pioneer, like all six members of the sub class it was allocated to Cardiff Canton, who intensively diagrammed their new charges on Railfreight Metals sector services. This included doubled up on the heavy iron ore trains between Port Talbot and Llanwern, a duty previously in the hands of Class 56s. The last to gain a full repaint into the Railfreight Metal scheme in March 1991, it swapped its sub sector decals for Transrail’s big ‘T’ branding in 1995. The fun couldn’t last and it was stored unserviceable by new owners EWS in November 1998 after being stopped with radiator issues a few weeks earlier. Fortunately, 37901 was acquired for preservation in September 2002 and moved to the Llangollen Railway in October 2003 where it was restored to working order. Always a popular presence at diesel galas, a sale to Colas Rail in 2016 and then Europhoenix in 2018, who quickly repainted it in their house colours prompting hopes for a speedy return to the main line. However, it wasn’t until June 2022 that it would achieve this goal, albeit flying under the flag of the EP Rail ‘spot hire’ subsidiary. Currently hired to Rail Operations Group to cover for overhauls to their existing fleet of Class 37s, 37901 was repainted back into Railfreight Metals livery in July 2024.

37902 British Steel Llanwern

Released to traffic in repowered form at the same time as Mirrlees Pioneer in October 1986, 37902 was rebuilt from 37148/D6848 and other than niggling silencer and turbocharger issues quickly showed the impressive reliability and fuel efficiency of the MB275T and Brush BA1005A alternator combination. Like several members of the Class 37/9 sub class it was initially repainted in the unbranded version of the new Roundel-designed triple-grey Railfreight image, and retained this appearance until the first months of 1991 when Metals sub sector branding was applied. The livery was further enhanced the following July by its naming British Steel Llanwern and the addition of British Steel crests and Cardiff Canton depot plaques. The name lasted just 15 months before being removed during a period of store and swapped onto 56054. Returned to traffic in early 1993, the locomotive retained its plaques into 1997, and was a regular performer on steel trains into the Midlands into the early EWS era. One of the last pair to be retired in January 1999 along with No. 37906, there would be no EWS heritage fleet reprieve and preservation for 37902. While there was a brief burst of optimism in 2002 when it was purchased by Direct Rail Services as an engine test bed, plans for a return to service were quashed and it was despatched to Sims Metals at Beeston in March 2005 for disposal.

37903

Flying the flag for their as-converted condition in Railfreight grey is 37903, the former 37249/D6949. Outshopped from BREL Crewe in February 1987, the former Eastern Regional machine quickly readjusted to its return to South Wales, having been delivered to Cardiff Canton in December 1964. Dedicated to Railfreight Metals duties, albeit with the odd coal turn, it was one of the first pair of Class 37/9s to gain the Roundel triple-grey livery in August 1988, although curiously with BR arrow decals rather than the aluminium castings afforded to most other repaints. Happily this was rectified by 1989, although Canton never did go so far as to apply depot plaques at the other end. Despite joining the Trainload Freight West fleet, later Transrail, in 1994, it retained its Metals brandings right to the final curtain in December 1998, EWS deciding not to authorise a required ‘C’ exam required for it to remain in traffic. Another victim of the non-standard nature of the Class 37/9s combined with accelerating Class 66 deliveries. 37903 hung on until April 2005 and was the last to be scrapped, cutting being undertaken by a Harry Needle team at Crewe Diesel Depot.

Each of the three versions is unique with different silencer configurations and nose side grilles depending on period, and they also feature the whole host of upgrades afforded to the other models in the third run which includes working roof fan on both DCC ready and DCC sound versions, switchable tail lights (right on, left on, both on), revised bonnet top doors, see-through radiator shutters with radiators behind, and engine room detail visible through the windows.

Saving the best to last, a comprehensive new sound project has been recorded with assistance from Europhoenix and UK Rail Leasing.

Both BR versions will be available both direct and through Accurascale's network of stockists, while 37901 in Europhoenix livery will be an "Accurascale Exclusive", coming with special presentation packaging, a limited edition certificate and available only direct via the Accurascale website.

DC/DCC Ready locomotives are priced at £189.99 and the DCC Sound Fitted locomotives are priced at £289.99, in line with our recent launch of the other batch 3 locomotives and delivery is Q4 2025!

Pre-order your Class 37/9s below, or via your local stockist!

Pre-order Your Class 37/9 Locos Here!