My special subject being aired now. For the past 12+ years, the RAF has operated the Sentinel R1, a very capable and sophisticated piece of surveillance kit that all you one-time aircraft spotters will know about, and the rest can read more here.
The Sentinel has been of extraordinary value to HMG, in ways that will not find detailed expression in the public domain but you can readily imagine. (Start by searching on Operation Shader to get the general idea.) Osborne, that f*****g 'genius' whose entry in the history books will be 100% damning, decided to scrap them for cost-cutting reasons but Cameron was persuaded (well, begged by our allies) not to follow through, so they were given a 5-year life extension.
But now their last mission has been flown, and there's no 1-1 replacement in sight.