AIRBUS may be forced to delay the launch of its £7 billion A350 project because Christian Streiff, the group’s new chief executive who has still not formally started work, needs time to approve the venture, The Times has learnt.

Details have also emerged for the first time of how NM Rothschild & Sons came to its valuation of BAE Systems’ 20 per cent stake in Airbus, casting doubt on the effectiveness of work done by other City institutions.

Sources close to EADS, the majority shareholder in Airbus, have given warning that M Streiff, former deputy chief executive of the French conglomerate Saint-Gobain, may not be able to make a decision about the A350 by the company’s self- imposed deadline of the Farnborough Air Show, which starts on July 17.

Officially, EADS insists that a decision on the A350 is still possible by Farnborough but neither it, BAE or Airbus has been able to confirm exactly when M Streiff will be confirmed as chief executive.

He was nominated last weekend after Gustav Humbert, his predecessor, was ousted because of delays to anther project, the A380 super-jumbo.

M Streiff’s appointment is not expected to be confirmed until the start of next week — about the same time that Airbus is understood to have scheduled meetings formally to approve the A350.

That could give M Streiff, who has no aviation experience, only days or even hours to come to grips with this enormous project.

A source said: “There is a possibility of him saying the A350 project is too much for him to give an OK to when he is just days into the job.”

A City analyst said: “After the production delays for the A380, another delay in another project would be hugely damaging for Airbus. However, it is too important not to get right and longer term nobody will blame Streiff for taking more time.”

The A350 is a wide-bodied aircraft that will seat at least 250 and go head to head with Boeing’s new 787, dubbed the Dreamliner.

Airbus’s initial designs for the A350 did not receive a warm reception from airlines and the jet-builder was forced to draw up new proposals. This is thought to have caused a significant increase in development costs, with estimates now up to £7 billion.

These extra costs are one of the factors that led Rothschild to place a lower valuation on BAE’s 20 per cent Airbus stake.

A source close to Rothschild gave a robust defence of the bank’s valuation of the BAE stake at €2.75 billion (£1.9 billion). Most analysts had expected the stake to be worth about €4 billion.

Rothshild had complete access to the Airbus books. Its evaluation of the impact of US dollar exchange rates on earnings, the value of launch aid, the value of credit guarantees and the long-term capital needed to finance the A350 and a revamped A340 and A320 were all factors that led to the €2.75 billion figure.

A City source familiar with Rothschild’s work said: “You have to say the quality of analysis by other banks has been poor. I think the Airbus business has not been that well understood and the liabilities are also not well understood.”

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