My father used the Bury electrics to commute from Bury or Radcliffe to Manchester. In his opinion the data used to justify the proposal was a complete fabrication of the actual use. I think those who reviewed the closure were equally unimpressed.
Trains used to run every 10 minutes in the rush hour and there were some extras starting from Prestwich.
I don't normally try to justify or condone the "lies, damned lies and statistics" used in many of the Beeching proposals - but I do wonder, with some of the busy commuter routes which were unexpectedly listed to be axed, if someone was looking at the
trends in their usage.
A good few well-established commuter routes saw a steep drop-off in patronage from the mid-1950s into the 60s as car ownership grew. If you did have a car, it wasn't out of the question at that time to commute into Manchester or Liverpool and park every day in the city centre (especially if you were someone living in the more prosperous suburbs and were entitled to a company car). Which eventually translated into less frequent trains in both peak and off-peak hours.
I suspect the Bury line might have been one of these victims. When BR built the fleet of Class 504s in the late 1950s, they seem to have built far too many for the traffic offering, meaning a good number of units went into long term storage at the back of Bury depot and eventual scrap with few miles on the clock (and still in green livery). I believe the North London and Watford DC lines saw the same thing - resulting in the LMR having too many 1950s-build Class 501s than they really needed.
Thinking charitably, maybe BR management at the time drew trend lines for the lines' falling usage over the past 5 or so years, extrapolated straight lines into the future and so concluded "by 1973, the trend line will hit the axis - there will be zero passengers using the Bury line". Of course, nothing in nature or society goes in straight lines for very long.
Having traveled on the line in the last years of the service, BR did their best to run it down with the most uncomfortable stock I have ridden in. (Mind you the early years of Metrolink had the trams swaying and crashing from side to side. I was surprised the drivers could keep control of the tram. I don't know what its like now.)
There's regular discussion in these forums of the 'lively' ride to be had on the 25kV Class 304 EMUs around Manchester. Definitely true in many circumstances - but I recall the Class 504s (which were of similar vintage) could certainly be relied on for a good bounce when they got up to any kind of speed on the Bury line's jointed track. I can't remember this 'feature' being mentioned much until now - and whether any of Longsight's (allegedly incorrect) bogie maintenance procedures were repeated at Bury depot.