LONDON, July 6 -- Four times, easyJet Plc's (LSE: EZJ) board said no. Castlelake, the Minneapolis-based private equity firm, kept raising its price anyway, and on its fifth attempt it finally got the answer it wanted.

The board agreed in principle this week to recommend Castlelake's offer of 690 pence a share, cash, valuing Britain's largest budget airline at roughly £5.2 billion and rising to £5.5 billion on a fully diluted basis, or about $7.3 billion. That is a 73 percent premium to where easyJet's stock closed on May 29, the day Castlelake first disclosed its interest to British regulators. It is also the number that finally cleared the bar the board had spent a month insisting the first four offers did not.

The sequence t...