I am struggling to see why Heliair would need Booker. They would help themselves, it appears, if they did all their certification work at Wellesbourne. It seems silly that the crates arrive at Wellesbourne, the Robbos get put together and then ferry flown to Denham for their CofA and any final bits of "completion work". Just last week Denham was too busy and two new Raven IIs had to sit at Wellesbourne for days until Denham had the space.
And there's nothing to stop a training flight taking off from Denham and then using Booker's circuit, is there? Or even base two or three at Booker rather than buying the hangars.