I know this should be on the Army thread, but I would like to remind everyone that when we had Leopard tanks we had well over 100 of them. And before that we had Centurians, again well over 100 of them. It is only our recent acquisition of American tanks when it was found we only needed half the number. I would have thought that the number should have increased over the years, not shrunk.
While I agree that we should have more tanks than we do, I very much disagree with the thrust of this, which is that the number we had in the past should determine the numbers we have in the future. I find that to be very lazy thinking.
For starters it's worth pointing out that the Abrams purchase replaced the capability we had in service at the time - it replaced two squadrons of Leopards with two squadrons of Abrams. There was no reduction in the number of in service vehicles.
More to the point, why should we look to the past for what we should have in the future? Surely the numbers of equipment we have should be based on the strategic outlook of now and what we can predict about the future, not on what we happened to have in the past.
There's lots of ways to point out this. For instance, at the end of WWII we had many hundreds of tanks in service. Should we then have many hundreds in service now? Of course not. Those many hundreds were required for a six-year global conflict in which the entire nation was mobilised, a conflict that bears little resemblance to our current strategic outlook. The opposite here is also true. How many attack helicopters did we have in service 50 years ago? Should that be taken as justification for not having attack helicopters now? Of course not.
Any justification of numbers must be based on the current strategic outlook. Any other justification, particularly those related to the past, are irrelevant and unhelpful.
For what it's worth, I think a realistic number of tanks under Plan Beersheeba, based on the strategic outlook and realistic funding and strategic priorities, is three 4-troop squadrons or four 3-troop squadrons, which is about the same amount (and effectively a doubling of the tank capability - about another 36-40 tanks). Plus engineer variants.