The video shows hundreds of rank-and file sparks trying to prevent Balfour workers entering the site as part of a national day of action.

The film highlights tensions between demonstrators and some of the workers who break the picket line.

It also shows deteriorating relations with the police as tension rises leading to a number of confrontations and arrests.

The rank-and-file electricians are planning similar demonstrations every week as part of their campaign against planned changes to the JIB pay and conditions agreement.

The next flashpoint is expected to be Kings Cross Station on Wednesday

To watch the video click here