Despite his impeccable suits and impressive government contacts, Don Cruickshank is not "one of us". He has no old school tie, no Oxbridge background - he studied at Aberdeen University - and his parents were teachers, not stockbrokers.

The London Stock Exchange's (LSE) more activist board members wanted someone who could shake it out of its complacency, and the 57-year-old Mr Cruickshank clearly fitted the bill.

His recent track record in tormenting British Telecommunications as head of British telecoms regulator Oftel, followed by his hard-hitting report into banking "`rip-offs", have marked him out as a reformer.

Few doubt he will shake up the City's oldest institution, which for 200 years has been controlled by an uneasy coalition of East End traders and Old Etonian corporate financiers.

But while the LSE wanted change, its owners and customers might have preferred more certainty about the future than Mr Cruickshank is prepared immediately to give.

He insists he has no "vision" for the exchange, and rather than talk about a possible merger with Deutsche Borse in Frankfurt, he takes a typically intellectual view of the market's role, comparing it with the "networks" in telecoms and banking.

Looking out of a 23rd floor window, Mr Cruickshank cheerily admits he had been in the stock exchange tower only once before his appointment. No wonder everyone was surprised he got the job, for which he was approached by headhunters in January.

He took the position, he said, because he felt exchanges were being fundamentally changed by technology, by the LSE's "commitment to change" following its demutualisation and merger talks with Deutsche Borse, by the European dimension of the role and because he thought "it's a worthwhile job".

Whether he will command respect from the companies listed in London is another matter. His report on the banks went down badly in the Square Mile, attacked as "ill thought through" by consultants and as "confused" by bank chiefs.

But Mr Cruickshank says the banks will be stronger as a result of his recommendations, and better able to compete in Europe. Does he have the same aims for the exchange?

"The patriotic, nationalistic political background to this is really quite unfortunate," he said. "For Europe as a whole in this area, as well as others, learning to set aside national interests is absolutely critical."

He argues that exchanges are fast disappearing as physical concepts. The important thing for London is that it continues to retain the "clusters" of talent and organisations that have made the City the premier international financial services centre, thanks among other things to the liquidity and transparency of and trust in its markets.

"That, historically, is what London has provided," he said.

Mr Cruickshank's description of himself as a "European Scot" might not go down well with flagwavers in the City but is likely to prove popular with the international investment banks that make up the exchange's biggest customers.

Persuading the vested interests of investment banks and retail brokers to see eye-to-eye could be helped by his background. A former McKinsey consultant, he helped float Sir Richard Branson's Virgin empire then take it private again - and is one of the few managers to emerge from Virgin without falling out with Sir Richard.

Mr Cruickshank sees his three principal tasks as chairman as supporting the LSE's existing management, accelerating its transformation from a mutually owned to a shareholder-owned company and representing it abroad. That's quite a workload for a position that he will fill two days a week as non-executive chairman.

A particular challenge will be reconciling the interests of all the exchange's users - from the global investment banks to private clients.

No matter who controls the exchange, there is no doubt that it has a role as the point at which the public interacts with the City. But Mr Cruickshank believes that is largely a historical legacy.

"It is important that the functions of the LSE play a big role in the UK economy," he said. "But it is not a public service."