Unexpectedly high losses at Mindscape, Pearson's ill-starred US CD-Rom investment, was only the latest disappointment, the investors said. The company remains unfocused and its clutch of assets too diverse. "At the very least, the company should announce as soon as possible a successor to Barlow," said one large investor, as a first step toward a radical reorganisation.
Moreover, an internal successor, the preferred option for Pearson's current management, is unlikely to satisfy institutional shareholders. Among possible candidates from within the company are Greg Dyke, head of Pearson Television, and senior executives David Bell and John Makinson.
Mr Barlow's successor is scheduled to be named next year. A Pearson spokeswoman said last night: "I am sure shareholders are looking for comfort and reassurance. It remains our intention to move on the issue next May."
Senior management, including Mr Barlow, have been meeting with shareholders since the beginning of this month, and further contacts are expected until well into June. Pearson declined to comment on the substance of investors's comments, although the spokeswoman confirmed that shareholders have been asking about succession plans.
In recent months, Mr Barlow has overseen a restructuring of operating units, introducing clearer lines of management control. But the company remains what one analyst last night called "a typical conglomerate: unfocused and underperforming."
Some investors came to Mr Barlow's defence yesterday, however. "He has made a real effort to transform the company," said one. "But he has not always been able to carry his board."
Pearson has been the subject of intense speculation in recent months, as the market lay bets it would either be taken over or forced to accept radical demerger proposals. While shares have shot up in recent days, they have still underperformed those of other media companies in recent years.
News that Mindscape would post losses of up to pounds 46m this year particularly infuriated some shareholders. "It is clear that no one is taking responsibility for the disaster at Mindscape," said one.
The company has received proposals from two sets of advisers - Barings and McKinsey - laying out ways of enhancing shareholder value. These include a radical break-up plan, creating several companies out of one. Henderson Crosthwaite, the City broking firm, has calculated a breakup value of up to 900p a share, compared to last night's close of 712p.
Among the proposals is a plan to spin off the company's television interests, worth about pounds 700m. Reports over the weekend about the possible spinoff helped push the shares up 13p yesterday.
These assets - which include Thames Television, Grundy Worldwide and US-based ACI - are believed to be among the most attractive.
It is also believed that Pearson Television's Mr Dyke would be interested in seeing a separate listing for his subsidiary, and is uncomfortable with the "culture" of Pearson's head office. But a spin-off would leave Pearson holding less valuable book publishing and lesiure assets, as well as its Mindscape subsidiary.