This may seem like a daft question, but what happens to the old aircraft once they are taken out of service.
Are they just broken up, sold to other countries or mothballed in the event of the 3rd world war?
They're not mothballed unless we really are planning to resurrect them in the future - once they're out of service nowadays thats it, because the level of manufacturer support disappears to nothing, and most importantly, they would still remain declarable as treaty-limited equipment. The rest depends on the aircraft and country really. We don't tend to flog them off to other countries at that age and for that type of aircraft. The general order of events from last operational station is to strip out non-type specific role equipment which has been identified to transfer for use on other aircraft, then fly to the airfield from which they are to be disposed. Strip out remaining equipment that is not for disposal to the outside world and carry out recovery of other spares if other nations are operating the type and are interested. Where it then goes is determined by the aircraft type (i.e. who else wants/do we wish to have a combat aircraft), its age, fatigue life remaining, how flyable/maintainable it is, and whether spares support remains available etc. For something like Jaguar, other than another military force, it is unlikley to be of interest as (unlike the Canberra) it is a reheated high performance low level jet. Moreover, the only place that currently allows such aircraft in civilian use is South Africa - neither the CAA nor FAA do because of the potential danger involved in joe civvie playing with that level of complexity and supersonic performance. The other aspect of course is that their systems have become increasingly electronic orientated. So, by and large, after all that, some will go to museums (one is in the new Cold War museum at RAF Cosford) and the rest will head back into the melting pot.
And now that I'm on the computer at work, here's a nice still picture of the Cat at work in the Lake District...
MG Mark