We probably could quite easily - sell the current relics and get a couple of BBJs & Gulfstream Vs on a partial wet lease with RAF crewing. Probably work out cheaper than maintaining our present knackered old fleet. So many other countries around the world manage to provide proper VIP transports - why can't we?
That said, I do think the current fleet of 125s and 146s have a very British "Faded Glory" tattiness about them and are a very appropriate way of delivering the architects of our national bankruptcy around the world....