THERE will be no tears on Tuesday, says Lord Marshall. Then he pauses. “There will, I suppose, be a degree of emotion.”

At 11am, at the Queen Elizabeth II conference hall in Westminster, he will open his last annual meeting at British Airways. He has headed the airline for more than two decades, first as chief executive, then as chairman. This week Martin Broughton, former boss of BAT, replaces him.

The end of an era? Without doubt, because Colin Marshall, alongside former chairman Lord King, was the key man in the team that dragged BA through privatisation to become one of the most successful airlines in the world.

The problem is that in more recent years there have been profit slumps, job cuts, accusations that the airline has lost its way and calls for Marshall, a man who collects directorships as casually as others buy new suits, to trim his workload and step down — calls that started years before he finally announced the move.

Did he hang on too long? Marshall, medium-height, craggy, sitting in shirtsleeves at the offices of Pirelli UK — yet another company he chairs — pouts momentarily.

“Too long? Well, you can always say that, but it is a matter not for the individual but for the whole board, whether they want a person to continue. Our long-term planning in bringing Martin Broughton on board four years ago was to anticipate this day. The whole issue was one of timing, from the BAT as well as the BA standpoint.”

He talks slowly, carefully, in the gravelly manner of an ageing City grandee, which at 70 he has every right to be.

But Marshall has always been more than that — in his time as chief executive, he was one of the leading managers of his generation. Born and brought up in north London, ambitious enough to emigrate to America to make his fortune, then to return 20 or so years later, he has stuck with big companies all his career.

What he gave to BA — his upbeat, Americanised, anti-hierarchical style of management, and a transatlantic expertise in marketing and customer service — was a breath of fresh air for an airline coming out of state control. That turnround made him one of the most admired figures in aviation.

“He is one of the reasons I came to the company,” says BA chief executive Rod Eddington, previously boss of Cathay Pacific.

“He is universally respected because of how he turned a state-owned airline into a forward-looking, customer-focused business.”

Being a chairman, though, has not been easy. Under fire after the Higgs report for chairing more than one FTSE 100 company, then criticised as firms where he sat as chairman or deputy chairman — BA, Invensys, Inchcape, BT — plunged into trouble, Marshall has been an embattled figure since the turn of the millennium. But will he admit it? It’s not in his nature.

“People need to understand and look at the situations in greater depth,” he says, clasping his hands. Only when he stumbles over the reasons for Inchcape’s problems — “it was heading into trouble because of the collapse of the Japanese yen, um, or was it the strength of the yen?” — do you realise that the amount of detail he has to master must be taxing.