The Chinese bank, the world's fifth largest, signed a deal to buy a 20 per cent stake in the family held Paris-based Rothschild asset management and private banking business. The French government applauded a deal that appeared to mark a breakthrough. It also seemed a sign of a tangible improvement in Franco-Chinese relations after the summer row over the pro-Dalai Lama demonstrations when the Olympic flame passed through Paris.

For the first time, the Bank of China was taking a stake in a eurozone financial institution as part of its efforts to develop the necessary expertise and products to serve its 130m depositors. For the Rothschilds, it was not only a vote of confidence in their banking savoir faire but offered one of Europe's oldest and most aristocratic banking houses an opportunity to expand in the Chinese market.

Yet nearly four months on, the deal has not been consummated as it awaits official clearance from the China Banking Regulatory Commission (CBRC). Indeed, the original agreement between the Chinese bank and Rothschild expired at the end of December, although the two parties have extended the closing deadline to the end of March. The Rothschilds are not only puzzled by the seemingly endless delay in securing the CBRC's rubber stamp, but are starting to become irritated.