The merging of boundaries between the public and private sectors would appear to make it easier for individuals to move between them. But the perception still is that government service and commerce are worlds apart. The experience of Derek Lewis at the Prison Service and Sir Richard Greenbury in chairing the committee on executive pay shows that success in one sphere is not necessarily repeated in the other. How Bill Cockburn will fare by moving in the opposite direction, from the top spot at Royal Mail to WH Smith, is, of course, still to be seen.

The perception persists, despite research suggesting that a high proportion of key public positions are filled by people from outside. Nearly 40 per cent of senior appointments by public-sector employers last year were from either the private sector or not-for-profit organisations, according to a survey by the executive recruitment firm NB Selection. But the same employers strongly believe that the less prestigious image of public-sector management continues to deter applicants from the private sector.

Private-sector job candidates did not share this view: they believed that there were rewarding opportunities in the Civil Service and related areas. They agreed, however, with their public-sector counterparts that perceived employer prejudice within the public sector reduces the number of cross-sector moves. More than half of candidates applying through NBS for public-sector positions strongly believed that potential employers in this area would be reluctant to recruit from elsewhere.

So muddied is the whole area that the report, Bringing New Skills into the Public Sector, finds evidence that, for instance, senior executives in many public-sector organisations feel that a lack of understanding of the nature of accountability in the public service prevents many private- sector people from moving across.

Moreover, many executives report "frustration with the poor quality of private-sector candidate presentation and preparation". They feel that many private-sector applicants do not make the effort to learn about their business. Equally, though, candidates feel frustrated that public-sector employers see them as "a product of their organisational background, rather than as people with skills and knowledge in their own right".

But for all this, the survey found that some transfers between sectors worked. There were several factors behind this.

External recruitment works best where:

a significant change of programme is to take place and a leader is needed;

a challenge has to be faced, options formulated and implemented quickly;

the organisation looks like a private-sector business and an eye for revenue generation and opportunities is required;

the post calls for financial skills or business acumen;

organisations recruit to the middle, promote to the top and time is given to the proper induction and mentoring of recruits.

It does not seem to work so well where:

organisations are in a steady state and people already there see outsiders as supplanting their "rightful" career prospects;

a chief executive is brought in from a different environment and not inducted into the politics of the organisation and sector.

Similarly, there were clear signs of which types of people were likely to succeed. Those most in demand by the public sector were experts in human resources, information technology and financial management.

But Margaret Walker, of NBS's public-sector practice, who carried out the survey, wants to go further and find out how the public sector can select candidates most likely to make an effective transition and help them to prepare better for the process.

If this sounds daunting, there is encouragement to be had in at least one finding - pay no longer seems to be a problem. Employers feel that salary terms and conditions offered are on a par with those in the private sector, while only a third of candidates applying for public-sector positions advertised by NBS thought salaries an issue.