Over 220 Prospect members working as curators, conservators and managers are angry after a decision to defer payment was imposed without consultation.

In one case the three-month delay will result in some members losing up to £2.500. Staff in the Science Museum, National Museum of Film Photography and Television and the National Railway Museum - which collectively make up the National Museum of Science and Industry - will also take part in the protest.

Members voted overwhelmingly in favour of taking action short of a strike, (92 per cent of the vote), which from Monday February 16tth will see staff work strictly to their agreed hours and a ban on unpaid overtime, which the museum depends on to keep functioning.

Management has argued that it was necessary to delay implementation of the deal because it faced a deficit of around £600,000 largely because of the government’s failure to properly compensate the museum for the extra costs associated with introducing free entry.

Alan Leighton, Prospect national secretary, said: “Our members are intensely proud of the museum and its place in our national life. They are a very dedicated group who understand the financial pressures facing the museum as it struggles to maintain ground-breaking exhibitions and retain free admission with insufficient Treasury funding.

“But this has left a sour taste in their mouths as it was the first year they had expected to have a reasonable pay rise, and measures to begin to address the pay and grading anomalies, after 10 years of below par awards. Once again the Department of Culture, Media and Sport is relying on the goodwill of staff to keep the museum going, rather than put in the resources that are so vitally needed. ”

The 2003 deal of 5.3 per cent was viewed as a step forward in closing the considerable gap between museum staff and, for example, colleagues on comparable grades in the DCMS. If the government does not increase funding to realistic levels, the museum will be forced to make further cuts in activity, Prospect has warned.

The union is urging the public to support a week of action beginning on February 16, which coincides with half term, by visiting the world renowned exhibitions made possible by the dedication and commitment of staff.