Aer Rianta and its partner NatWest Ventures will pay £80 million for a 40 per cent stake in Birmingham International Airport (BIA) if the deal is completed, according to a confidential memo. The document, which was circulated to the seven local councils which own the airport, also reveals that Aer Rianta is "highly unlikely" to proceed with the investment if BIA's expansion plans are curtailed or delayed. Page 4