>Now all I need to do is convince the expenditure committee >that I need a 2.8 70 - 200 !
That's easy. Find articles about the holy trinity (14-24, 24-70, 70-200), leave them lying around in view. Talk about how $6000, when you think about it over the lifetime of a good lens, is not so bad (say $2/day).
Or print out some specs (with prices showing) on a 400/F2.8.
After you hint around about these for a while, the expenditure committee might find it easy to compromise down to the 70-200 only.
Though looking at your equipment you have a lot of overlap in the medium zoom range already with both the 24-120 and 70-300, and you do have a camera good at high ISO.