Environment Minister Michael Meacher had been due to discuss the controversial Welbeck landfill site at Normanton with Paul Dainton, leader of the residents' action group RATS.
The group has waged a 15-year campaign against the huge waste disposal which it says is Europe's biggest toxic tip.
Mr Dainton was to have confronted Mr Meacher today on various issues relating to the site's operation.
But he was stunned when he heard of the shock resignation of Mr Meacher on Friday as part of the Ministerial reshuffle announced by Prime Minister Tony Blair.
"It took two years to arrange this meeting with the Minister. I am bitterly disappointed," said Mr Dainton, whose vigorous campaigning against Welbeck led to an injunction banning him from setting foot on the site for life.
The meeting was also to have included representatives of the Environment Agency and the site operators, Waste Recycling Group (WRG), two organisations of which Mr Dainton has been fiercely critical.
"Everybody was geared up for this meeting and then this happens," he said. "Friday the 13th was certainly not lucky for us, and we are now back to square one again.
"I don't know what we are going to do now. There has so far been no indication that this meeting will be re-arranged for some future date, and I suppose I will have to start writing again to see if another date can be fixed.
"One minister has agreed to meet us so I don't see why his replacement shouldn't agree to do the same."
Mr Dainton had been planning to ask the Minister why no court action had ever been taken against the Welbeck site operators, despite dozens of breaches of site licence conditions.
Today a spokesman for new Environment Minister Elliot Morley said it far too early to say if the meeting would be rearranged.
The spokesman added that it was not yet known whether waste would be part of Mr Morley's portfolio.
alan.y@ypn.co.uk