The internal documents of the time don't mention that as a reason. At the time BR had four different 125mph and above electric traction projects on the go: APT, Class 89, HST-E and Class 91. The decision was taken by the InterCity sector that this was an extravagant use of design effort, so the first three were cancelled and effort was concentrated on what became Class 91 and Mark 4 stock.
Did Brush design and build these locomotives before B.R. decided on what they wanted ?
Falcon was built in response to a BR request for technology demonstrators, the BRCW Lion and DP2 came out of the same request. Falcon, Lion and the Hymeks all took note of a design brief from the Design Bureau. DP2 didn't.
Falcon was one of the three 6 axle designs that BR requested (along with Lion and DP2). Basically they wanted a more modern loco instead of the 8 axle Peak, with all axles driven (rather than 2 carrying axles). It led to Brush type 4 and must have been successful as a design because last 20 Peaks were switched to class 47s (which is why first 20 class 47s had different equipment including ETH and boilers, as equipment had already been ordered)
After selling Kestrel to the Russians, do you happen to know why Brush had the first thirty class 56 locos built in Romania, which surely would have been a commonist country at the time ?
They had no spare capacity on their production lines in Loughborough at the time, so they contracted out the construction of the first thirty locos to Electroputere at Craiova.
The story which has long done the rounds was that DP2 used a spare Deltic bodyshell: it's possible this is not quite factual. Could simply have been that the Deltic bodyshell jigs were still in place so it was simple just to build an extra one.
Ceausescu had tried to make Romania non-aligned as far as global politics was concerned. From time to time this led to western leaders seeking to have better relations with him. The 56 contract happened during such a period.
To add, at a similar time, the BAC 1-11 aircraft was licensed to be built in Romania as well.
Apparently the Soviet ТЕП70 (TEP70), a Co-Co single section of 2944 kW passenger locomotive, were directly derived from Kestrel. As the ТЕП70 had a fuel saving of 10-12% less than the predecessor ТЕП60, one presumes Kestrel impressed. Believe about 300 were built for use in Central Russian and Central Asia. As the only spotting I have done in that vast country was in western Russia, sadly never got to see any (and only seen one ТЕП60).
That's intriguing as I've seen published online a translation of a supposed Russian report that they felt Kestrel didn't offer any advantages over their own self-developed technology. According to that they gave it a series of trials, then gave up on it.
A mystery wrapped up with ... well ... probably a whole load of vodka. Is not as if the Soviets have not got past form on such technology transfers, as seen by reverse-engineering the Boeing B29 into the Tupolov TU4. Certainly the ТЕП70 body shape is very different from Kestrel, yet the overall morphology is curiously the same. Will go with your analysis ... the truth is a mystery.
After the lessons learned at Brush with the Kestrel project, is it likely that some of the technology was used later on with both the class 60 and class 89 locos. ?
Dunno about that, but the cylinder heads on the 58 are said to owe more to Sulzer than EE
D49 is definitely not a copy,firstly because Kestrel was bought by USSR in 1971,and D49 was already mass produced and used on TE109(1968)and TGM6(1966) by that time,secondly is that the design and specifications are very different from LVA engine.It is,as far as I know is the first type of mainline locomotive four stroke diesel engine completely developed in USSR after WW2.
About TEP70,I don't think it was copied off the Kestrel either,because in terms of design,systems, these locomotives are very different.For example,in TEP70 radiator cooling fans are driven by hydraulic axial-piston pumps,whilst in Kestrel it's AC motors.List can be continued, they are really different locomotives in terms of design.
Being a Toton man at the start of my driving career, and having driven both BREL, and Romanian built 56s, I do have to say that despite not being as user friendly or solid as the BREL 56s, the Romanian one's did seen to build power up a lot faster, making for an enhanced driving experience with heavy trains on uphill gradients.
