In message , at
13:41:52 on Sat, 8 Apr 2017, michael adams
remarked:
My technical knowledge is limited but as I understand it anyway
this was because of wheel flats, and the problem was solved eventually
by refacing the effected wheels on lathes.

Now while on the one hand maybe, taking a belt and braces approach
to maintenance is uneconomic in today's climate, nevertheless IMO
this isn't a situation which shouldn't have been allowed to develop in the
first place.

If there's a massive leaf-fall (as happened last Autumn as a combination
of medium term weather conditions plus one of the big storms) the only
way to prevent the wheel flats would be to stop running the trains. And
passengers already get cross when trains are scheduled to run slower in
leaf-fall season.

Having got the wheel flats, they literally can't be fixed overnight.
--
Roland Perry