Miners at Tower colliery, near Aberdare, would have lost pounds 19,000 a head by maintaining production until privatisation at the end of the year with no guarantee of a buyer.
About 250 members of the National Union of Mineworkers voted at a mass meeting to reverse last Friday's decision to work on following pressure from management, miners who wanted to accept the package, and four other unions which had already opted for closure. NUM members calculated that a weekly pay packet until the end of the year would not match the enhanced redundancy payments on offer.
The colliery will now be kept on a 'care and maintenance' basis in case a private company decides to bid for it. Tower made pounds 28m profit in the last three years, but BC wants to close it following a fall in demand for power station coal.
Miners took the decision despite a personal plea by Arthur Scargill, president of the National Union of Mineworkers, who visited Tower on Monday. Mr Scargill condemned the corporation for conducting a 'dirty tricks' campaign.
Yesterday British Coal confirmed that a 'non-negotiable' national offer would be presented to miners' leaders which would maintain the maximum basic redundancy payment of pounds 27,000. The extra pounds 19,000 on offer to Tower men would not be available after this month.
Colliers would have to agree flexible working practices in order to qualify for the new package, corporation sources said. A lump sum of pounds 6,000 would be paid to miners on acceptance of the new deal.
Although yesterday's decision by the Tower men came as a surprise, BC sources pointed out that some 70 miners had earlier expressed an interest in taking the enhanced redundancy payments.
Tower miners voted on Friday to accept a British Coal offer to keep the pit open, but the NUM subsequently contacted management informing them that they were reconsidering the decision.
All other unions at the pit, Nacods, the pit-deputies, Cosa, the white-collar NUM branch, BACM the managers' union and GMB Apex for administrative staff, had already reached agreement with the corporation on taking redundancy.
Ann Clwyd, a Labour employment spokeswoman and MP for Cynon Valley, yesterday clashed with the Speaker, Betty Boothroyd, in the Commons after claiming that David Hunt, the Secretary of State for Employment, and British Coal were 'peddling untruths'.
Similar unparliamentary language got the Prime Minister into trouble recently. Mrs Clwyd was told three times to withdraw accusations that Mr Hunt and British Coal were 'lying through their teeth'.
Mrs Clwyd staged a 27-hour sit-in at the pit last week, emerging from underground when British Coal agreed to postpone its closure.
She said the Government's pit closure programme had forced thousands of men on to the economic scrapheap.