Don't want to be a stickler but our man asked how much it costs to run the Army. What we've shown him is the Defence Budget. There's more to UK Defence than just the Army. The Navy for example; I've heard that their ship costs a lot to run.
What we really need is an efficiency comparitor between the services, a sort of MPG for defence, except we could compare operational effect to £ spent. That'll be fun.
Hard core financial stuff, but this is the best you will get. Running/Maintaining is an operating cost. Other capital costs such as building infrastructure, buying kit etc will not be included in operating costs.