Colin McKerracher, the former chief constable of Grampian Police, said the very creation of a single force was a “political move”.
He said: “The police didn’t want it, the public had no great appetite for it, so why did it happen? It happened because the SNP government wanted to ‘brand’ it Scottish, along with the Scottish Health Service and Scottish Fire and Rescue Service.
“We are now seeing that it is not working. Police are in the headlines for all the wrong reasons now – failing call centres, senior officers complaining about other senior officers.”
Mr McKerracher, 63, said Justice Secretary Michael Matheson had been “let down” by his officials, who should have prevented him becoming involved in plans to allow Police Scotland Chief Constable Phil Gormley to return to work while complaints against him from fellow officers are investigated.
Mr McKerracher said: “Government officials should have told him to keep out. This was a call for the Scottish Police Authority, as the employers. I can’t think of the process which made him think he could become involved.
“The whole issue of Mr Gormley’s ‘gardening leave’ is bizarre. I have never heard of a chief constable being put on gardening leave.
“He should have been suspended, as any officer from a constable upwards would have been, which would have ensured protection and clarity of the process, keeping everything clear in the minds of all those who have been affected.”
Mr McKerracher suggested it was time for “internal restructure”, by structuring Police Scotland along the lines of London’s Metropolitan Police, which is one force, but there are many command areas, with commanders at chief officer level.
Mr McKerracher, a CBE and holder of the Queen’s Police Medal, said establishing four or five command centres across Scotland would allow the single force to respond to the different policing needs in different parts of the country.
He added: “Even before the introduction of Police Scotland, the politicians decided Grampian should have a motorway unit. There are no motorways in Grampian. But we had to take 24 officers away from community policing to keep the politicians happy.
“It was also decided each part of Scotland should have the same access to a specialist firearms unit. Yet the need for such a unit differs widely across the country.”
He said one of his biggest disappointments has been the loss of accountability through the abolition of local police boards, made up of local politicians of various political persuasions.
The watchdog body which replaced police boards, the Scottish Police Authority, is made up of political appointees.
A Scottish Government spokesperson said: “The independence of operational policing is clearly enshrined in the Police and Fire Reform (Scotland) Act and we will continue to support the service to carry out its work, free from any political interference.
“Police reform was widely supported on a cross-party basis and with recorded crime having been reduced by more than a third over the last decade, public confidence remains strong.”