Professor Susan Deacon

Professor Susan Deacon said in her resignation letter to Justice Secretary Humza Yousaf that these are “fundamentally flawed”.

“There is little more I can do to make these arrangements work effectively,” she states.

Professor Deacon was appointed in 2017 in order to bring a “fresh perspective” to the post following a series of rows on the operation of the SPA.

In her letter, she states she has made “every effort” to ensure the current framework worked “as I believe it was intended”.

Scottish Liberal Democrat justice spokesperson Liam McArthur MSP said: “Susan Deacon did the best she could with a broken system. Liberal Democrats have been telling the SNP government since day one that it hard-wired flaws into the national force. It botched the centralisation, causing chaos.

“The national force hasn’t had stable leadership at any point in its six year existence. How many more chief constables and chairs does it need to quit to drive this fact home?

“Overstretched officers and staff deserve so much better, particularly since we found out that the job is making many of them unwell and only three per cent believe the force really cared about them.

“Powers over policing should be shared, rather than hoarded on the desk of the Justice Secretary. An independent expert review of how policing structures are operating is essential to inject accountability, transparency and localism back into the system.”

Scottish Greens justice spokesperson John Finnie said: “Susan Deacon was hired to give the police watchdog renewed drive and focus, part of which requires the SPA itself to be politically accountable for its work. In her statement, Ms Deacon appears to question the need for political scrutiny so it’s right she should go.

“It is vital that the Scottish government now finds a way to ensure the organisation can provide adequate scrutiny – and stand up to it - going forward.”