Let us not forget the RAF Regt mini-tanks. It was/is all about defending the airfield perimeter, and beyond. I subscribe to the idea of 'specialism', but just wonder whether the back-up infrastructure justifies the costs.
4th Battalion the Blankshires, suitably equipped and trained on a permanent basis, could do the same tasks without the 'baggage' of an RAF Regt Depot and associated MoD or HQ Air staffing.
I know it's heresy, and I apologise, but in the smaller UK Mil we have today there are surely savings to be made.