Part of the celebrations to mark the 20th anniversary of the National Coal Mining Museum for England were cancelled last month because of a continuing pay dispute.

Action by the museum's 110 staff, including the threat of picketing, forced the cancellation of the annual Miners Gala and the closure of the museum for a day.

Commercial director Richard Saward said a work to rule had been instigated, and that the museum had also closed for two days over the May bank holiday weekend.

He estimated that the museum had lost 3,500 visitors over the three days, costing it between £7,500 and £9,000. "We weighed that against losing our £2.75m grant if we broke government pay guidelines," he said.

Staff union Unison wants a 4.2 per cent pay rise. But the museum's management claimed it was bound by Department for Culture, Media and Sport guidelines to stick to the current offer of 2.5 per cent over three years.