Recently we've seen a growing number of government employees who have been recruited by private companies with a commercial interest in public services.
Trained for decades and well-remunerated in a senior Whitehall role, only to retire early with a generous pension and then be paid even more to help a private company sell business back to government. It is not hard for taxpayers to feel that personal interest and private sector gain wins out in the current system.
This is an issue across Whitehall and the whole criminal justice sector. Top Ministry of Justice officials have taken early retirement, or voluntary redundancy on the Coalition's generous 2010 scheme, only to resurface months later working for a private firm in the same sector.
Probation chiefs were less than impressed to see Phil Wheatley, the former head of HM Prison Service, now working for G4S - the corporate security giant that runs several private prisons and is in line to take over some probation services.
Rules state that senior civil servants (and political advisors) must seek permission before accepting a new private-sector role. But permission can come with lax conditions and there is no sanction scheme - in essence former staff are trusted to avoid conflicts of interest.
Two factors are driving this. First, the marketisation of public services in an effort to break up monopolies, raise productivity and cut costs, which is creating more demand for this talent. And secondly, pension rules in the public sector that make these people available for a second career.
As public services are opened up, new job opportunities emerge for those who have spent their career so far in public service. Private companies who are bidding for public sector work, clearly think top civil servants with senior contacts, policy insight and Whitehall experience can help them do that successfully. On the operational side, chief police officers are some of the most sought-after individuals in the security sector.
The issue here is not the choice that individuals make which is entirely up to them. But the system that means one reason they are in demand at all is because there is a supply of personnel that is leaving the public sector so early.
Outdated public sector pensions that allow staff to retire with comparatively generous pensions in their early fifties when they would be in the prime of their working life in any other career, means top talent is lost from the public sector a full decade early, and private companies benefit.
In a free society, people cannot be told where they cannot work and we must trust that former public servants see and avoid the ethical dilemmas that might arise in a private sector role. But along with a register of lobbyists, we may also need stricter rules to govern employment of former chief officers and top Mandarins, like those that apply to Ministers, who cannot engage in commercial activity linked to their government portfolio for two years.
Unless rules are firm and clear, this revolving door risks corrupting the public procurement process that depends on fair competition. It may also undermine trust in government and reinforce the notion that public services can be exploited by private companies and their well-paid directors, not improved by them.
Blair Gibbs is the Head of Crime & Justice at the think-tank Policy Exchange