BR / BTC came very close to having class thirty eights. You can trace this back to the very development of the CSVT engine which was the obvious successor to the SVT even by the time the first D200s had completed commissioning.
Further the last orders for 37s were seen as being largely a freight dedicated batch and EE apparently offered the "bone" cabbed 2000hp locos they sent to east africa ( now sudan and somalia)
What form would the class 38s or class 40/1s have taken though ?
This is a fascinating flight of fancy in fact. There are several possibilities.
Firstly the earliest solution would have been a production run of 2000hp D6700s. There may have been radiator modifications, perhaps a higher capacity boiler. One option EE may have taken up though could have been dual heat with a boiler space and space for a straight six 450 hp auxiallry motor ( a duplicaiton of the boiler / Engine space as penned in the sales panphlet to BR for D6700) . This would have needed more legnth to fit the additional equipment and allow for longer range fuel tanks. Weight would have then pushed up about 6-8 tonnes for the frame and tanks and 2 tonnes for the engine : thus making an RA6 loco. EE would have kept the proven deltic/D6700 gearing although fitted cast bogie frames and stronger armature equipment to tackle the extra thrashing.
EE also offered the v16 CSVT at the then "safe" 2350hp rail de-rating, approximately the same as the D6700 as lowered from marine / power station rating per cylinder. This rating ended up in the successful C1800s of Portuguese railways. Brush were also in the picture here as locomotive manufacturer! This before the class 31 type was re-engined with the 1470hp SVT version of the v12.
There were several precedents for brush being asked in: one they had produced a 2000hp class 31 with a air charge cooled Mirlees unit, and they had worked on peaks by that time in the very early 60s. The other being that BTC/BRB did want a degree of standardisation but wanted some wider perespective in delivery-solution and not being too bound to one supplier.
However neither were to be, and it took EE making DP2 and BRCW's Lion to move things forward for more modern, lighter weight type 4s to start appearing in production by the mid 1960s.
By then EE had more experience of the CSVT engine and were confident that the then full marine rating was just as applicable to rail traction. It wasn't long after D449 was delivered that the RK engine gained over 3000 hp for marine application and went on to 3250 and more in the mid seventies.
So EE offered the 2000hp in the "east african railways" design, probably with ETH as an option. However BRB declined and stayed with the same strategy as the D200 order- it is standard as a class by numbers now, don't fix if it aint broken.
Type 3s and the newly ruston re-engined almost type 3 Brush type 2, were proving themselves to be very useful: tackling especially freight diagrams previously larger or multiple steam locos were seen on, and also taking over the diagrams of mid powered steamers like the black 5 and castles in generally excellent fashion.
Meanwhile the type two investment showed itself already to be a folly because the underpowered "rats" were often needed paired up to work even 300 ton trains and the single unit traffic they had been built to command, was drying up post Beechings and the rise of the lorry and motorway. There are enough "standard gauge" railways in the world at that time for the standard LDA6 loco fleet to have been decimated down by sale to needy railways with less ambitious speeds and a requirement for low gross weight of locos over poorer trackbeds and bridging. Some of the "rat" classes should have been upgraded to the far superior LDA 8 engine as type threes to join their more successful cousins as type 3s, which became the Class 33.
350 to 1000 tonne freight was where the railway excelled and on the passenger side, the intercity and express cross country and commuting services were also the economic area the railway could win in, and these diagrams remain so today and will become more so in future . Type 3s could command the lower end of this tonnage in single units, and the larger end would prove to be economic for a long time as double units until the advent of SEPEX and the american creep control systems enabling single units to start 1000 tonne plus trains.
So in 1964 to 65 the BRB could have decided to take up EE's offer for a 2000hp 12 CSVT based, slab end loco. However rather than being a substitute for the last 40 or so D6700s, an order for a new loco class, to be the "little sister" to the then planned EE type 4 production run from the success of DP2. What form then a "syphon Super G!" ??
Well by then the order for a new class would have been with slab ends but most likely with internal walk through for driver safety and inspection "on platform" of internal mechanism failures. An extended order of D6600s to 2000hp with ETH fitting could have been another tantalising possibility. However there was also a dwindeling number of RA5 lines. Perhaps a new 2000hp loco would have been given higher weight and for freight dedication, a lower gearing like the 20s and later CP7 bogies?
I like to think that an EE super-syphon would have been in effect a mini fifty with pleasing tumble home sides. It would have probably retained blue star, buffer level multiple working and hence, as the original d400, with an elegant roof level horn box and route indicator below cab window. Thus it may have resembled a cross between the D400 and the shorter, lighter C1800 exported to Portugal.
What gap in the haulage requirements of the mid to late 60s would this loco have filled ? Well given a full dual heated, stretched RA6 variant then it could have been employed on the then rather common expresses to reginional cities and towns from the then partly electrified WCML which were then served in the early 60s still by steam, d200s and peaks: the latter being total overkill for hauling load 6 to 8 on a 40 to 70mph route. The first generation DMUs were already proving troublesome on trans penine and other express and semi fast services so there was another chance to displace these to their rightful place on regional stopping services. Other diagrams and routes for an ETH / dual heat class could have been cross london with Southern region stock, and dragging southern region units around like 33/1s but maybe on routes like the MULE or as above, cross london or SE to SW services.
A 2000hp loco at RA5 with ETH and standard gearing would have as an alternative, been a very useful bit of kit replacing for example type two double headers on ex WCML route5 s to Aberystwyth and the WHL. We must also remember that the crown prince of passenger traction weighed in at a humble 105 tonnes, the supreme Deltic. Light weight was seen as the key to good power to weight delivery and high speed by EE despite the tendency to wheel spin.
This is another little issue on the electrcial power delivery : EE were ready with AAA arrangement for traction motors with independent current reduction per motor as implemented on the class 50. How much use would this have been on a class 37 with even more horse power ?
The final tantalas I present is then also a matter of electro-mechanics: 1) would the locos have the KV10 style sensibility 2) would EE have dared to use a fourth field diversion to a final, higher voltage enabling 95-100mph "cruising" ? Post 1995 bashers don't believe that the humble 37 could top 100mph in single form. They would have day-in-day out on the Glasgow-Edinburgh run and in pairs on the Super west country services (replacing and supplementing Westerns). The Kv10 could have rendered the locos actually more reliable or with a cheaper service because in theory it reduces driver demanded overloads and hence wheel slip. At the same time it would have deminished the real strong point of 37s- being able to groan up gradients on high amps at decreasing speed.
The one over riding question would be if the CSVT unit in the 1960s form should have ever gone to the rating of 167 hp per cylinder : 50s were experiencing engine block cracks in the 1980s, while 37s rode on and could have remained as a class of over 150 locos today given the traffic for them on Ra5 routes. Inherently a multiple of three , 120', is a smoother engine for an equivalent per cylinder rating because the power delivery pulses are more balanced ; this is the dub in the fifties. 37 292 was a lame machine when I had it, but was that due to the uprating or to a lack of up-rated maintainance on the valves and timing chain ? I think a fleet of 2000hp super syphons could have seen their wings clipped by dertaing to 1850 or all the way to D6700, but also they would have been standard enough, new enought and useful enough to have gone through HGR and received alternators and CP7 bogies.
In the 1970s there was no stomach in reality but for the highest performance end of freight and passenger ( HST) and the ECML was still planned to be electrified. Had we never had diesel hydraulics or so many vermin type 2 sulzer slugs then there would have been an obvious gap for a light type 3 / 4: Sulzer offered the v8 version of the LDV engine for example or derated v12s to various customers. Also the fuel crisis could have set the scene for the reduction of type two multiple working and the slowing of type 4 diagrams. Type 3s and the Brush 2, have all been quoted as being the best fuel economic locomotives relative to the broad duties they tackled.
At least EE fans can look back at the various machines: the ever ready 08's and 20s, the magnificent stop gap deltics which long out lived their design missive, the duplicitous 50s- soveriegn when working but flawed in original complexity and even HGR remodellign, the robust class 40 and finally the ubiquitous, all conquering class 37 : a locomotive which spanned 50 years of railway history, working the legnth of breadth of the Uk, tackling everything from the heaviest freights, the most challenging routes and even propelling the APT on speed trials on the ECML : the most renown and resolute of all classes by nature of their ability to take on more than they were designed for and to live longer than anticipated to the joy of railway fans the legnth of Blighty!!!