Sir David said that he would be resigning from several key posts when he took over from Lord Cairns as chief executive of SG Warburg on Monday. He said then that he would need all his time to concentrate on rebuilding Warburg's fortunes.
Sir David also resigned from the BBC board of governors yesterday, an appointment he received last year. He remains a non executive director of Chubb and the longest serving director of the Bank of England.
Sir David was tipped as a possible successor to non-executive chairman Lord Prior when he joined GEC in 1992, though that had increasingly been seen as unlikely.
Warburg is GEC's main financial adviser and Sir David has known Lord Weinstock for many years. However, Lord Prior's partnership with Lord Weinstock has gone from strength to strength. Analysts said that the chief executive's controversial decision last year to remain at the company for another two years is expected to seal the relationship further.
One analyst said: "Sir David's departure is unlikely to have much lasting impact on GEC because the company has a large board of non-executives. The departure would have been more significant last year.''
This was a time when shareholders were calling for a more balanced board, and Sir David was seen as instrumental in providing opposition to Lord Weinstock.
The analyst said: "But Weinstock's decision at the last annual meeting to continue his tenure suggests GEC is still dominated by one individual. After then, Sir David's position was seen as not as potent as it was.'' Another analyst added: "His leaving will be seen as more to do with problems at Warburg than anything to do with GEC.''
Sir David is famous for having a wide spread of interests and is a fully paid up member of the "great and the good."
He was made a governor of the London School of Economics in 1993, for instance, and in the same year became a director of London First, a campaign to promote the City's interests.
When Lord Cairns became chief executive of Warburg in 1991, Sir David took a more back seat role at the bank which he had built into a global force. Sir David nursed ambitions to succeed Sir Robin Leigh Pemberton as Governor of the Bank of England, but was beaten to the post by Eddie George. Sir David picked up the reins at Warburg last weekend, and has since been working hard to restore morale and convince employees that Warburg has an independent future.