Ministers increase pressure to raise strike ballot threshold

Union leaders argued they had a convincing mandate for yesterday's strikes but ministers claimed that the patchy support reflected the turn-out in the ballots which approved the industrial action.

In their propaganda battle, ministers repeatedly cite the 32 per cent turnout in the Public and Commercial Services union ballot, meaning that less than 20 per cent of its members actually voted in favour of yesterday's action.

The Government is under pressure from Tory MPs to reform industrial relations laws so unions would have to secure a turnout of more than 50 per cent in ballots before action could go ahead. The Confederation of British Industry has suggested a 40 per cent threshold. Dominic Raab, a Tory MP, said yesterday: "What you can't have is a very militant minority inflicting maximum damage in vital public service infrastructure on the hard-working majority, when it's got such little support."

Boris Johnson, the Tory Mayor of London, who has faced a series of strikes by London Underground workers, renewed his call for a 50 per cent threshold. However, he conceded that politicians would not always clear such a hurdle in their own elections. Ministers say there are no immediate plans to change the strike laws but that the issue could be considered in the event of a wave of co-ordinated strikes this autumn.

The TUC argues that a minimum threshold would be riddled with anomalies. For example, if 499 workers out of a workforce of 1,000 voted Yes and nobody voted No, a strike would be illegal. But if 251 voted Yes and 250 No, it would be allowed. "This is clearly not about democracy, but simply about making it difficult for unions to call strike action," said Nigel Stanley, the TUC's head of campaigns and communications.

So what kind of turnout does give a mandate?

Public and Commercial Services (PCS)

Turnout in ballot: 32.4 per cent

Proportion of members voting Yes to strike: 61.1 per cent

National Union of Teachers (NUT)

Turnout in ballot: 40 per cent (state schools); 27 per cent (private schools)Proportion of members of voting Yes to strike: 92 per cent

Association of Teachers and Lecturers (ATL)

Turnout in ballot: 35 per cent

Proportion of members voting Yes to strike: 83 per cent

General election 2011

Turnout: 65.1 per cent

Coalition parties' share of the votes cast: 59 per cent (Conservative 36 per cent; Liberal Democrats 23 per cent)

Number of MPs winning more than 50 per cent of the votes cast in their constituencies: 219 out of 650 (34 per cent)