From 6.30 this morning there were long tailbacks of worker traffic as the protesters besieged the gates of the base, sitting down in the roadway and locking on to each other. Two climbers scaled lamp-posts and hung across the main gate of the base a large banner reading "Nuclear Free Scotland". The base was disrupted for almost nine hours as gates cleared by police were blocked again by activists.

The MSPs arrested are Mark Ballard, Francis Curran, Rosie Kane and Patrick Harvie. Along with the others they are likely to be released from police custody this evening.

The blockade has now been closed with a formal ceremony but further actions against the base may be taken during the rest of the day.

Overnight two Scandinavian activists, Tiina Sarkinen, 23, a plant scientist from Finland, and Anna Goransson, 24, a student from Sweden, swam into the high security berths where the Trident submarines are berthed and got 200 metres inside the boom before being apprehended. Early this morning Petter Joelson (27), from Goteborg in Sweden, and Per Hilkrstrom (22), from Nosrkoping in Sweden breached security at the Trident nuclear warhead store at Coulport on Loch Long, five miles from Faslane.

A Big Blockade spokesperson said: "We are delighted that so many people have been willing today to take a stand against Britain’s weapons of mass destruction."

The Trident Ploughshares camp at Coulport continues until 1st September, with the prospect of further direct action against the Trident bases.