Healy Mills was just one of the many 'modernisation plan' hump shunting yards . . . The complete and utter waste of money spent developing this concept was one of the more striking mistakes of BR, but it's really a whole subject in itself.
Consolidating freight operations into these larger yards seemed very rational at the time I'm sure, potentially saving many staff and facilities at smaller yards and speeding up wagon transit times. The complete collapse of general UK railfreight, except for a relatively small hard core of highly profitable bulk flows, was not planned for in the 1950s and was a result of many factors outside of BRs control, so it's not correct to claim modern yards were a great failing of the BR's modernisation plan itself, but rather it's terms of reference from government. Large yards, usually equipped with humps, continue to operate in Europe and the US today, so its not correct to claim the concept itself was obsolete then or is today.
If we're looking for aspects of the modernisation plan to criticise, continuing to build steam engines whilst at the same time acquiring a bewildering array of largely untested different diesel locos and units was probably a more serious tactical error, although most of the evidence of that has since been recycled into cars and cans of beans many times over by now! The rusting overgrown yards remain however.
Whilst they are largely out of use now, at least some of those vast tracts of brownfield land in the abandoned yards could be considered for safeguarding for future railway use, for freight growth, depot sites etc, although probably not exactly in their former use for humping!
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