"Imagine," said PCS general secretary Mark Serwotka, "what a difference it would make if we didn't only march together but took strike action together." The cheer that resounded from the crowd in Hyde Park spoke for itself. This was 26 March, the day that half a million workers from across Britain turned out for the most significant manifestation of trade union strength in decades – although you may remember it as the day when some windows were broken.

However inspiring 26 March was, though, leaving it at a march from A to B – just in time for local elections – would be a terrible waste. Some union leaders may feel that the best use of this energy is to vote Labour in the May elections. But Labour councils are also pushing through cuts, and it is obvious from local strike ballots that union members aren't putting up with this. The next logical step is, exactly as Serwotka says, co-ordinated strike action. So, the Public and Commercial Services Union (PCS), National Union of Teachers (NUT), University and College Union (UCU) and Association of Teachers and Lecturers (ATL) unions are moving towards balloting their members for a one-day national strike over pensions, job losses and wages.

What sticks out here is the participation of the ATL, which is a professional teaching union not given to militancy. Its last strike action was in 1979. Similarly, the Royal College of Nursing (RCN) overwhelmingly passed a motion at its annual conference in Liverpool calling for an indicative ballot of members for national strike action. This is far from typical for the RCN, which, until a change in its policy in 1995, always ruled out industrial action. The "proletarianisation" of professionals in the public sector, with degraded conditions even for usually respected staff, is leading some of the traditionally conservative unions to be more militant than their larger counterparts.

If the strike ballots are approved by the members, this could result in up to 800,000 people taking strike action. If other small unions join the strike, there could be over a million people taking industrial action on that day...