I am getting bit tired of the 'long trains all of the time' obsessives here, who time after time choose to ignore the basic fact that IETs are replacing plenty of short formations, in the shape of the 180s and Turbos operating to the likes of Oxford/the Cotswold Line and to Bedwyn. And replacing HSTs used for jobs like Paddington to Hereford or Cheltenham off-peak, where there has been nothing else better suited to the service available, due to the limited supply of 180s. And offering the ability to not send hundreds of empty seats into Cornwall all day round for large parts of the year.
All services where one of the 700-seat behemoths - complete with a buffet and lashings of hot food, of course - would be utterly inappropriate most of the time.
As for all those getting misty-eyed about October 1976, one of my abiding memories of my first encounters with an HST was a Swindon to Paddington run - off-peak - where people had to stand, as there simply weren't enough second class seats just a couple of weeks after the trains entered service. Those passengers affected probably couldn't have cared less that the formation included both a restaurant car and a buffet car. Nostalgia isn't all that it is cracked up to be.