Aer Lingus is uniquely vulnerable to Ryanair’s advances, according to Michael O’Leary, in spite of the rejection of his latest bid on Monday night.

The budget airline’s aggressive chief executive certainly knows his Irish rival intimately. He knows where he would cut costs, where he would make money and where Aer Lingus loses it. And he knows how he would face down the notoriously truculent unions at the smaller airline, if they opposed a takeover.