A fascinating fact about defence budgets is that no matter what the changes in the strategic situation the proportion of the budget assigned to each of the three armed services hardly changes at all – proof, if any were needed, that defence policy is the product not of rational decision-making but of bureaucratic processes.

As the Ministry of Defence ponders how to face a new era of financial stringency, there is a danger that this bureaucratic process model will triumph again. Planners will heed calls to maintain a “balanced force”, and will cut evenly across the department, avoid hard decisions, and refuse to set clear priorities. They will succumb to interest-group pressures to maintain high-cost items (Trident and aircraft carriers, for instance), and compensate by extensive cuts to the other elements of the military without which those larger-cost items are useless.

The only way to avoid this is to reconsider basic assumptions. As there is no direct military threat to the United Kingdom, defence spending is justified by the idea that Britain must project military power overseas. Three assumptions provide intellectual backing for this policy: that the world is an increasingly dangerous place; that military intervention makes Britain, and the world, safer; and that defence spending raises Britain’s prestige. All three assumptions are false.

First, in the past twenty years the magnitude of conflict worldwide has declined by over 60 percent. The need for large-scale armed forces has rarely been smaller. Second, recent experience belies the concept that intervention overseas increases Britain’s security; it probably does the opposite. Nor does it make the world a better place. A group of economists working under the rubric of the Copenhagen Consensus has examined what forms of international intervention provide the best value for money in terms of enhancing global welfare. Unsurprisingly, military spending came well down the list. And third, there is little evidence that military activity increases Britain’s prestige; recent failures in Basra and Helmand may well have done the opposite. But even if it does, there is even less evidence that increased prestige produces proportionate material benefits. Concrete examples of such benefits are hard to come by.

There are still a few activities which the military can usefully fulfil: surveillance of Britain’s territory; military aid to the civil power; search and rescue; counter-piracy operations, and so on. A rational defence review which focused on these activities would permit large cuts in spending while simultaneously ensuring that the military is capable of doing what it should be doing. Unfortunately, this is not likely to happen. More probably, the interests of the defence lobby will prevail, producing a bureaucratic compromise which will continue to waste national resources in futile pursuits overseas.