The action is over a below inflation cost of living increase, which averages just 2.5% for many and penalises the most experienced staff with pay increases of less than 1%. The row over pay has rumbled on since the settlement date of August last year, forcing union members to protest by withdrawing from non-essential duties.

Those duties include the issuing of fishing vessel certificates and the MCA information line which will affect out-of-hours information given to the public and shipping companies.

PCS members are also refusing to complete end-of-month returns and incident reports, hitting the information and statistics made available for ministers.

‘Management could have avoided damaging industrial action by negotiating seriously and offering decent pay to those who deliver a vital emergency service,’ said PCS general secretary Mark Serwotka. ‘Below-inflation pay is completely unacceptable with the basic coastguard grade paid barely above the minimum wage at £5.37 an hour for a 42-hour week.’

Staff who monitor shipping and public safety across tens of thousands of square miles of ocean and coastline feel betrayed and have been further angered about the total disregard of the pay comparison evidence with other 999 services, he added.