Mr Cameron has presided over industrial peace since a bitter nine-week national strike won the arrangement in 1978.
He was determined, he said, that his firefighters would not return to the days when some of them were forced to claim state income supplements and free school meals. 'My members risk their lives and deserve better,' he said.
For the Fire Brigades Union it is a highly emotional issue. Ministers will ignore the mood among its members at their peril.
The union could be in the vanguard of the most serious industrial unrest John Major has faced since he became Prime Minister. A series of 24-hour strikes could easily lead to a 'lock-out' by hawkish local authorities and an indefinite dispute. The Ministry of Defence would no doubt press the Army's old 'Green Goddess' fire engines into service, leading to a propaganda battle that the Government would be no more certain of winning than the one of 1978 was.
Pay will not be the only issue. Mr Cameron is determined that the public will also see any industrial action as a protest over the threat of redundancies and deteriorating emergency services.
The ambulance workers fought a six-month dispute in 1989-90 to gain a pay arrangement similar to the firefighters', backed by a wave of public sympathy. And this time the firefighters could be taking action at a time of serious upheaval elsewhere.
Mr Cameron will ask his union's annual conference in May for a free hand to judge the most propitious time for a ballot, enabling him to synchronise action with other public-sector workers.
Nalgo, the local government union, started a campaign against the Government's 1.5 per cent upper limit on public-sector pay, as well as job losses, on Thursday, with a series of rallies, marches and stoppages. But a summer of unrest for local authorities could prove a mere backdrop to the more serious challenges from the Conservatives' traditional 'class enemies'.
The firefighters will have a potential ally in RMT, the main rail union which, as the Independent revealed yesterday, is expected to announce on Monday a decisive vote for a series of day-long stoppages over compulsory redundancies, cutbacks and the threats posed by privatisation.
This action is likely to be timed to coincide with a 24-hour miners' strike on 2 April to protest at the Government's pit closure plans. Both the rail workers and the miners will argue that they are attempting to defend their industries - a contention that might elicit public sympathy.
Last week the EC published figures showing a dramatic drop in strikes in Britain. But the historic low of 34 days lost to strike action per employee in 1991 is clearly already out of date. The graph has begun to climb back up. The first glimmer of militancy - and the first stoppage of any consequence for some time - came in February, when 1,300 workers at the Yarrow shipyard walked out over pay.
Unrest then surfaced at Ford where, for the first time since the company set up in Britain, white- collar staff, angry over the threat of compulsory redundancies, voted to take action. The Ford management abandoned a plan to make some manual workers compulsorily redundant at the mere suggestion of a strike ballot.
But the industrial scenery had already begun to shift last October, when the Government and British Coal announced their plans to close 30 collieries with the loss of more that 30,000 jobs. The success of union demonstrations in forcing a ministerial U- turn has had a lasting impact.
Last week's Budget - seen by the unions as unfairly singling out the low-paid - coupled with an incipient economic recovery, and the strong possibility of the Chancellor's Autumn Statement imposing a further ceiling on public-sector pay, could all add up to a new period of industrial conflict.
The Government must hope that assurances about redundancies in the rail industry could its defuse problems there. Even a series of 24-hour strikes by miners may have little impact, given that many in the most threatened mines have already taken redundancy.
But the odds are that a 'summer of discontent' could be followed by an autumn and a winter of much the same.
More than 1,000 Fire Brigades Union members were in Victoria Street last week to demand industrial action as their union leaders emerged from a meeting with Kenneth Clarke, the Home Secretary. How to handle the firefighters is the most delicate - and potentially the most damaging - problem for ministers.