HST's (which is what my dad always called them) are still in service with ScotRail as well as with Great Western and Cross Country I think. As mentioned elsewhere, some have gone to Mexico and others to Nigeria. I'm just sad that the line over Rannoch Moor isn't suitable for high speed running.Nerd alert! AWOOGA! ........
The HST/IC125 saved British Rail's bacon back in the 1970s (40% passenger increase in 4 years). A huge step change in journey times. I knew a number of the people involved with the development of the tilting APT (Advanced Passenger Train). Lot of advanced new world-first ideas for the time, boffins (some ex-aero), some problems, but they were almost there when That Woman cancelled it (in classic British fashion) and we now reap the rewards with the Pendolino tin cans, effectively buying our own technological breakthroughs back off the Italians. The APT guys were not well-liked by other engineers (some reports said they were banished to their own separate toilets!). When BR saw what was happening they tasked some of the more traditional pipe-smoking engineers to come up with a fairly "normal" but still very powerful (hence 125mph) alternative. Quick fag packet design, with some clever styling, and it was sorted in record time. Of course this is when we used to make things. As mentioned elsewhere the last ones have only just come out of service 40 years later.
Anyway, I was invited to a talk a couple of years back given by one of the fitters who worked with my dad at Bath Road depot in Bristol and later on the new HSTs at St Philips Marsh. In the early days of going into service, power car 43020 was notorious for losing power unexpectedly, so much so that it was unofficially known as Damien from the film The Omen, which also came out in 1976.
"So I climbed up into the fuel tank, a filthy box slung underneath which gleamed inside. It was quite psychedelic to be honest, plus there was the diesel fumes. Anyway I started to look for anything which might have been causing the engine to cut out. We'd taken everything else to pieces and checked it all twice; the fuel tank was literally the last place we expected to find anything, but there in the corner was a packet of sandwiches that someone must have lost back in Derby [where they were built]. It had been washing up against the outlet causing the fuel pressure to drop and the engine to shut down."
Damien was renamed Mother's Pride.
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