The best advice to retired executives who are thinking of criticising their successors is: don't. Carping former executives are usually seen as bitter, past-it and retrospectively attempting to justify their own records. Any merit in their criticism goes unheeded; people are too overcome by the stench of sour grapes to listen.

Recollections of Sir Edward Heath's time as British prime minister are not filled with affection or regard, marked as they were by industrial discord and national decline. But what really did for Sir Edward's reputation was his constant sniping at Margaret Thatcher, his successor as Conservative leader.

It is far better to maintain a dignified silence. If your successors really are as bad as you think, time, the polls or the market will unravel them. Leave it to others to voice discontent. Anything else smacks of disloyalty.

Of course, those who damn their successors protest that it is not disloyalty that drives them but the opposite. Anger at what is being done to the institutions they love compels them to speak out. And so it is with the eight former Morgan Stanley executives who have launched a bitter attack on Philip Purcell, the company's chief executive.

Intriguingly, the Morgan Stanley spat bears some resemblance to past Conservative feuds, particularly in its pitting of old money against new. Just as Tory traditionalists detested the public relations operators and property developers who surrounded the then Mrs Thatcher, so the Morgan Stanley Eight - representing the company's blue-blooded past - cannot hide their disdain for the financial services salesmen, headed by Mr Purcell, that the bank acquired when it merged with Dean Witter in 1997.

In their defence, the Morgan Stanley pensioners say that they went public only when the board ignored their private pleas. The eight are also shareholders in the company. So, having broken the golden rule of silence, are the Morgan Stanley pensioners going about their campaign in the best way?

Retirees, if they must speak out, need to get five things right.

First, the successors they are criticising must be doing a markedly worse job than they did. Does this apply to Mr Purcell? The eight say: "Over the last five years, the firm's total return has trailed the S&P diversified financial index by nearly 40 per cent." Five former Dean Witter executives counter that, since the merger eight years ago, Morgan Stanley's annualised stock return has been 15 per cent, outpacing the S&P 500. So it depends whose time frame and comparisons you prefer.

The second thing outspoken pensioners need to ensure is that they do not act alone. The eight cover a wide range of Morgan Stanley experience, from Parker Gilbert, who was chairman until 1990, to Robert Scott, president until he was pushed out by Mr Purcell in 2003. But all eight are from the old Morgan Stanley side; a few Dean Witter dissidents would have made their onslaught harder to resist.

Third, the former executives must reflect widespread feeling among existing employees. Here, the former executives appear to be on stronger ground. John Havens, one of the senior managers forced out last week, left to an ovation from colleagues.

Mr Purcell acknowledged the internal dissent in a memo to staff. He said that he was sure his actions were in the interests of employees, clients and shareholders, but conceded: "I know that some of you are not quite convinced."

Fourth, retired executives should act more in sorrow than in anger. They should stress their reluctance to speak up and emphasise how long they pondered the matter before doing so. They should acknowledge how difficult it is to lead the organisation, as they know from personal experience. They should add that times and market conditions change and that they appreciate how irritating it is to be second-guessed by those no longer in charge. But, having said that, and with great regret, they feel they have to bring to the board's attention.

The eight did none of this in their initial letter to the board, which they made public after Mr Purcell had, as they had feared and predicted, promoted his own loyalists over people such as Mr Haven and Vikram Pandit, another highly regarded executive who left last week.

They did say that they cared deeply about Morgan Stanley but then leapt straight into their blistering attack. "We believe that the overriding cause of the firm's poor performance is a failure of leadership by Philip Purcell as the firm's CEO," they wrote. "We believe that the current CEO will not be able to inspire and lead the firm back to its rightful position in the financial services industry. We also question whether he has the respect of industry peers or the firm's regulators necessary to the task of regaining Morgan Stanley's leadership in the industry."

Fifth, and most important, dissident former executives need a clear idea of how they are going to win. Who can remove Mr Purcell? Only the Morgan Stanley board. And what did the eight executives tell the directors? That they had "very little financial services experience" and that none had a background in the institutional securities that made a "disproportionate contribution to the firm's profits and reputation".

What is more, they wrote, although Morgan Stanley had its headquarters in New York, all the board members, including Mr Purcell, chose to live elsewhere. (Mr Purcell commutes from Chicago.) The board did not reply to this letter. I am not surprised.

Perhaps the eight former executives felt the board was so packed with Mr Purcell's loyalists that there was no point in trying to convince them. But it is difficult to see who, in that case, they expect to effect the chief executive's departure.

The former executives may have a strong case. Morgan Stanley, at present, sounds a miserable place to work. But someone should have told the eight to identify whom they needed to win around - and then remember not to call them idiots.

michael.skapinker@ft.com

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