When I joined the Cadets at school (early '60s) 'Jointery' was the new Gospel. In 25 years of military service I saw it work extremely well. There was some tremendous liaison, eg 42 Squadron and the frigate F42, HMS Naiad. I spent a week on board during an ASW exercise. My best experience of Jointery was at RAF Ballykelly in the early '70s when we had all three services living and working together on the same base. The banter in the Messes was fantastic, especially with three-and-a-half different sets of jargon. (The extra half was provided by the Bootnecks.)
However, the co-operation seems to thin out at Flag/Field/Air rank. I think it is a different mindset possessed by the serious career seekers who want to get to the very top. Empire building and preservation hold sway over rational inter-service allocation of resources. A good move might be to combine Greenwich, Camberley and Bracknell into one Joint Services Staff College.