Why not sell him a 5% stake in the aircraft for £1.00 that can be repurchased by the group at any time (or sold back to the group). That would sort out the requisite ownership element but would give the ability to take that 5% back in advance of a sale or (hopefully never) an insurance payout.
At the same time, you could agree different terms for this individual's actual flying but you'd want to be careful not to trigger any tax liabilities along the way (eg by making a profit, etc).