A couple of thought occurred to me when the smooth metals and third rail of the SR came to mind. Not a stranger to the RK derived 10 inch by 12 power units by any means, with the two Bulleid prototypes being commissioned for the long flat lines of kent, sussex and surrey. Not least also the some near sixty years of class 73 operations and over 20 of the thumpers. The Bulleid-EE prototypes would for better or worse influence phase one of dieselisation with their 1Co-Co1 configuration. Also that type 3 power levels could be entrusted with even 110mph services !
The final stub ended prototype was delivered as a type 4, setting the mould for the order of 200 of their lumbering, whislting off spring at 133 tonnes. At this point in time then we see the SVT power unit with 125hp per cylinder, which in a v12 is the magical 1500hp type 3. Later it was a purely artificial and arbitary derating to push the bruwh type ii into that category btw. So what about a series 1 fleet of v12 SVTs with co-co and noses ?
It would have taken extraordinary foresight to envisage that the traffic for type 1s and 2s would dwindle in the coming decade, and die in the 1970s. However the signs were there with the post war road revolution being more the csuse of the demise of economic viability of many branch lines and tiddley services, with Beechings being the messenger of ill wind, all be him partisan with a brother in law at the helm of none other than Tarmac Ltd. Four of the five v16 prototypes were all type threes, which were entrusted with a range of express and heavy services and paired for prestigious trains like the Royal Scot - given the teething problems and short service interval of deltics maybe both EE and BR-ER would have been bettr served by this "American" practice anyway.
The SR themselves would have both the need and foresight to order the sulzer based type 3 in order to meet their needs for ETH and offer superior speed and power to their underpowered straight six cousins. Type 3 would become a more suitable power for the types of freight business which became prevalent by the late 60s, and if you include the numbers from the 'almost a three' class 31, then the type three was more proliferate than type 4s rated under 2500hp. Type 3 is ideal for 250 - 400 tonne trains, which themselves today are no longer deemed economic as fayre paying traffic. 500- 1000 tonnes? , just double them up. Bar the sad decision on oil sloshing 'diesel hydraulics' and resulting drmise of the Hymeks, the other three classes outlived their inferior little sisters and nearly all of the type 4s, bar the ubiquitous down rated 'duff', and continue inuse as departmental and hire locos over the entire network.
If the usefulness of type 3 had been recognised in the early 1950 and the chance to run lighter weight locos with 4 less cylinders than their type 4 cousins seized, then surely this would have meant the following- a 1500 hp SVT LMR , ER and maybe ScR nosed, disc indicating, standard buffer beam co-co and larger orders of the sulzer-crompton across the same regions in addition to the SR. One would hope then that the same decision that belay the 40 and gave us a 1954 loco still being produced in 1965 would not befall the CSVT order , and rather coinversely that a c.1670hp intercooled sulzer would also happen!
Spectacular as D6700s could be in the hands of a driver keen for extra tea time on the WHL or up a welsh coal valley, they probably spent far more time singing away on notch 6 and 7 not 8 , thus putting out around 1400-1550 hp. SVT power through a 1956 deltic style commonwealth co co bogie although less spectacular, would be fully capable. At a light of fancy we could say that EE may keep up with the 8LDA of the 'shreddie' and rate the loco at 1550hp with an SR option for ETH. An order of 100 in 1955 ?
A 1956-60 operational 'sub syphon' could have found use on the steam vacs of SR's then numerous boat trains and the Mule route to Exeter. But its home land would no doubt have become that of the re-engines brush type ii, which may never have been built in numbers due to this competitor, and its big sister D200 fleet. Perhaps they would have been despatched also to work the Highland line out of Haymarket aloing side their contingent of the v16 sisters. I think that the v12 would have precipitated larger orders for the 1750 hp CSVT with perhaps a 2000hp variant as early as 1960. Also with the advent of 25kv towards the north and Scotland, perhaps the body would have had a 16 SVT plonked in it, no boiler needed for freights or ETH power on the un wired WCML?
Early EE drawings of their actual type 3, the D6700s, show a smallish presumably four cylinder ETH generator along the side of the boiler area, thus being dual heat, although it doesnt look like anything bigger than a small lorry engine of that time , maybe 180 hp.
That brings us to the other fantasy type 3 of say a 1958 delivery to BR. What if they decided to plonk a single deltic 18 into this type of Co-Co body shell ? With a smaller generator for ETH? Maybe even a non turbo t9 which could supply train boost amps power as well as enough for the 33 and 66 ETH ratings. Why not ? Apart from the CoBo, the baby Deltics were the most ludicrous of all the initial phase 1 diesels, with a tuebo power unit yet untried in rail application and a heavy body work defying the purpose of such a light motor. Napier and EE never actually promised more than 2000 hrs between overhauls, which means a strip down of the whole engine, so really the power units should never have seen the light of day in a humble work horse type 1 whose life would be spent in perpetual short thermal cycles best suited to lower speed marine derived units. More likely then, given the madness of the days, that there be offered a single T-18 deltic at 2200hp as a light weight alternative to the peak classes and the pedestrian D200s.
Thew concept of a 'multi use' body shell and bogie layout should not have been lost at this time. The LMS's prototype diesels were very heavy but had a lot of uneccessary weight in them like over engineered bulkeheads, buffer beams and bogie frames taken in design pretty directly from steam engine proportions. Hence the extra jockey wheels of thew bulleid design being specified. By the early fifties EE were producing lighter weight designs for export, culminating with the super light for so much power in Deltic. A standard design of body could have been used as a co-co of RA5 to Ra7 for different end purposes with different power units, most other equipment being standard onto , as became more or less, standard bogie design.
Common sense at BRB-BTC as well as production capacity at EE, Brush and BRCW were lacking in the 1950s unfortunetly however. Ironially enough, the phase II type 4s would prove to be in many ways to be inferior to their simpler and usually more reliable 1Co-Co1 predecessors. In fact though, bar the Hynek, the 33, 37 and re-engined 31 were all actually phase 1 orders, being placed before the review which would render everything twin window, slab end for the next quarter century until the advent of "skips". The diesel electric type 3s of course out lasted all the other phase I locos. Hindsight is a fine thing, but surely double as many 3s would have been only a positive develoment.