MARITIME union RMT yesterday demanded a public inquiry into the privatisation of the NorthLink ferries contract in 2012 after the discovery that a cheaper public-sector bid had not even been looked at.

Local newspaper the Shetland Times revealed this week that the bid for the Northern Isles ferry service tabled by public-sector operator CalMac — believed to be cheaper than that from Serco, which won the contract — was returned unopened.

RMT general secretary Mick Cash said: “These murky events cast a shadow over the tendering of CalMac’s lifeline ferry services to the Clyde and Hebrides, which is currently under way and which the trade union movement is fighting tooth and nail.”

He said it was no surprise that CalMac’s bid would have been cheaper than Serco’s, since the SNP government boosted the public subsidy to the latter firm when it privatised the contract in May 2012.

RMT believes that a subsidy increase of nearly £40 million allowed Serco to trumpet to the London Stock Exchange the winning of the £350 million contract for the Northern Isles ferry services.

Tendering for the 2016-24 Clyde and Hebrides ferries contract is due to open in a few weeks, but RMT accuses Transport Scotland of stalling over the details of pension and employment protections.

RMT national secretary Steve Todd spoke of a growing feeling that Transport Scotland and the Scottish government are going full steam ahead to the privatisation of Clyde and Hebrides ferries services, with the winning bid being announced after the Scottish parliamentary elections in May 2016.

“The revelations over their treatment of CalMac’s NorthLink bid does not bode well for Scottish ferry workers and the lifeline services they provide remote communities and passengers,” Mr Todd warned.