THE head of publicly owned ferry company David MacBrayne has stepped down following a series of terse exchanges with Government ministers, The Herald understands.

Archie Robertson, chief executive of the firm that oversees lifeline CalMac ferry routes, was officially described as being on annual leave for several weeks, fuelling speculation about his future. The company now refuses to confirm if he is still in post.

His departure follows the loss of a £40 million contract to deliver ferry services to Orkney and Shetland, which was handed to private firm Serco after Northlink, a subsidiary of David MacBrayne, failed in its bid to retain the service.

Mr Robertson had also been involved in several bruising rows with SNP ministers over the Gourock-Dunoon ferry service on the Clyde estuary, run by another David MacBrayne subsidiary, Argyll Ferries.

Asked whether Mr Robertson was currently chief executive of David MacBrayne, a spokeswoman said there would be "no comment". She similarly declined a request to deny that he had stepped down.

Richard Baker, Scottish Labour's infrastructure and capital investment spokesman, said: "This is a worrying development for those who rely on the lifeline services CalMac provides. Mr Robertson had concerns about the SNP Government's plans for the service, including de-bundling of routes and taking the Northlink ferries out of public ownership.

"It raises very real fears that the Government is hell-bent on privatising key ferry services despite concerns of the communities which rely on them."

Scottish Conservative Highlands and Islands MSP Jamie McGrigor said: "It is important David MacBrayne Ltd – and Scottish ministers – end the speculation surrounding Archie Robertson's future at the company as soon as possible."

Mr Robertson was appointed chief executive of David MacBrayne, a company owned by Scottish Government ministers, in June 2010 after heading up the Highways Agency, which is responsible for trunk roads and motorways in England, and working as operations director at the Environment Agency of England and Wales. Prior to that he had a 20-year career with oil giant BP.

His relationship with the Scottish Government was severely tested after Argyll Ferries won a contract to operate passenger ferries on the Gourock-Dunoon route from June last year, replacing the vehicle crossing with a passenger-only service.

Mr Robertson was not available for comment last night.