Softly spoken, immaculately dressed and with the gift of appearing utterly unflappable, Olivier Pécoux makes a fittingly urbane envoy for the world's loftiest financial dynasty.

“Investment banking needs severe regulation,” the co-head of NM Rothschild's global investment banking business says as he sips green tea in the serenity of the lobby of Mumbai's Four Seasons Hotel. “There is no question: things will never be the same again.”

It is rare that a banker admits to the inevitability of onerous new rules and it is rarer still for a Rothschild rainmaker to speak out. Over the course of nearly two centuries, from its City headquarters on St Swithin's Lane, the family-controlled financier of empires has carved out a reputation as one of the most private of private banks.

But Mr Pécoux, 47 — in Mumbai after a trip to Delhi, where Rothschild has opened an office in an effort to originate deals with the Indian Government, a possible prelude to privatisations — has his reasons for stepping out of the shadows. Rothschild is revelling in the fruits of its conservatism. There was a time when its position of offering only independent advice — and no balance sheet heft — to clients might have been seen as a shortcoming. Today, by contrast, its refusal to leverage itself and its decision not to stake its own money in the derivatives markets has left it looking much smarter than its embattled bulge-bracket rivals.

This is not to say that Rothschild's core mergers and acquisitions business has escaped unscathed. Russia, for instance, previously a big earner for inbound M&A work, has become “100 per cent a debt adviser business”, Mr Pécoux said.

Amid a dearth of credit, roles as lucrative as the bank's mandate in last year's £10.2 billion acquisition of Scottish & Newcastle have dried up. Nevertheless, Mr Pécoux believes that Rothschild represents a rare bastion of stability in a turbulent industry. “In this climate, boards want objective advice and clients appreciate receiving calls from the same banker. These are things that we specialise in,” he said. It is telling, the Frenchman added, that some of Rothschild's biggest rivals are not banks at all but elite management consultancies, the likes of McKinsey and Boston Consulting Group.

Mr Pécoux cemented his reputation by leading the defence of Aventis, the French pharmaceuticals group with which he had a long association, against Sanofi-Synthélabo in 2004, a deal where he helped to transform a €47.8 billion hostile offer into a €54.5 billion friendly bid.

His emphasis on the importance of nurturing relationships may help to explain his distaste for the mega bonuses earned by those traders who dealt in the ill-understood derivatives that triggered the global credit crunch. “These people, they were on a different planet,” he said. He endorses a more gentlemanly system of remuneration, one that values a banker's track record over several years and takes into consideration the willingness to share information with colleagues.

The notion tallies nicely with the Rothschild family motto: “Harmony, Integrity, Industry.” But that maxim discounts the opportunism that has driven the family bank from its earliest days — a trait better encapsulated by its founder's most famous saying: “Buy on the sound of gunfire.”

Nathan Mayer Rothschild, then 31, planted the family flag in the City of London in 1811 when he founded NM Rothschild & Sons. His masterstroke: the decision to finance the ill-fancied army being led by the Duke of Wellington against Napoleon. The British victory at Waterloo garnered him vast profits and cemented his family's influence for decades.

Ties with world governments remain and are being augmented. In the UK, Lord Mandelson recently asked Rothschild to advise on the future of Britain's beleaguered car industry. In the Netherlands it worked on the Government's €10 billion recapitalisation of ING, the bank.

Nowadays, however, compared to its swashbuckling past, Rothschild prefers to keep a low profile: interviews are rarely given; client lists, staff headcounts and financial results are guarded. For his part, Mr Pécoux makes clear that he does not envy his publicly quoted rivals. “It's not a desire to be unhelpfully secretive ... but look at Lazard,” he said. “There is no doubt that going public has proven a burden to them.”

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