Dermot may have actually got £750m in his bank account, but there's a whole raft of fees etc from the hangers-on to such a transaction to get to the final amount payable. Yes, that much more ! You need to get a "professional valuation".
"How much is the airport worth".
"Oh, let me have a look. Balance Sheet, P&L, yes ..... £750m.
"Good. Thank you".
"And our fee is 1% of valuation. That's £7.5m please".
"Here".
"It's a pleasure. Who is doing your 'second opinion' valuation, by the way .... ?"
Ad nauseam, ad nauseam. Not for nothing is Mergers & Acquisitions the most profitable part of City consulting work.