The InterCity HST 125s were the business! They saved main line Rail travel in the U.K. - the dieselisation programme had failed by then, much of the LHCS was at or approaching life-expired status and road traffic was rising rapidly.
I thought they were great. I used them a lot and their electric replacements are visibly derived from them; the 125s are still in use in areas of the network beyond the electrification grid.