Doubt anyone back then would have thought that 34 years later the same trains would be getting used on semi-fast commuter services out of Paddington.
Most maintaining them then would have been surprised if you told them they would survive 34 years, turbo charges failing, paxman engines "throwing legs out of bed", traction motor couplings failing, traction electronic controls failing, coach batteries boiling over (over charging), wheel side protection did not work, break disk cracking, coach vent fans failing, rad group leaks .................. etc
Having said that these were the first trains to go straight from manufacture and into service, the prototype bore little resemblance to the production trains
The
HSDT▸ 's were a stop gap until route electrification,
BR▸ did have the optimism in 1976 of full electrification by 1990!!!