Staff in the north of the country will leave their posts between 10-12pm while colleagues in the south, including the Saville Row London headquarters, will walk out between 2-4pm.

The action will affect leading tourist attractions, from Stonehenge to Hadrian’s Wall, as well as EH’s regional offices in Swindon, Guildford, Cambridge, York, Newcastle, Manchester and Bristol.

Nearly 500 members have voted to take industrial action, reflecting the frustration felt by members over yet another low pay award and an increasingly cavalier management attitude towards staff concerns. Staff are doubly angry that the award, which was due in August 2004, will be the second in a row that management have imposed.

Members say this latest low pay settlement is indicative of the financial crisis facing the heritage body, which has already resulted in a cull of skilled staff in education and architecture.

Prospect negotiator Dave Allen said: "These cuts strike at the very heart of the organisation’s ability to extend its educational remit into schools and colleges, while its architectural resources, which are so well-used in the preservation of the country’s physical heritage, will be diminished.

"Despite claims from Culture Secretary Tessa Jowell that ‘the arts and culture have never before had access to so much public investment’ the most recent government grant-in–aid allocation delivered a 4.7% cut in funding over the period to 2007-08. Factor in inflation and in real terms this is closer to 8%, despite more than 15,000 of EH’s 370,000 listed buildings being deemed at risk."

This latest squeeze on funding, coming on top of years of underfunding, has, said Allen, forced English Heritage to focus on exploiting the profitability of key sites such as Stonehenge to maximise income, to the detriment of its stated role.

"Instead of preserving the nation’s cultural heritage DCMS have left English Heritage struggling to appease its undervalued staff. But the decision to impose another poor settlement and bypass any consultation process with the unions has forced staff to make a stand."