The entire Tory group on Lancaster City Council walked out in protest at a meeting over police funding cuts.
Conservatives left Morecambe Town Hall and went home after their leader accused Labour of “wasting local taxpayers’ time”.
Labour councillors shot back, calling the walk-out “disgusting” and “an insult to democracy”.
The walk-out on Wednesday night was over a Labour motion on feared government cuts to Lancashire Police budgets.
The county’s police force was recently rated “outstanding” just days after its chief constable Steve Finnigan warned the service would “not be viable” after 2020 because of expected government funding cuts.
Councillor Brendan Hughes gave a speech claiming cuts could halve the Lancashire police budget by 2021 – a total loss of £161m per year.
“Make no mistake, the way policing is undertaken in every part of this district is changing, and in my opinion, for the worse,” said Coun Hughes.
He then called for the city council to write to Home Secretary Theresa May about the issue.
But Coun Peter Williamson, leader of the Conservatives, said: “Here we have another debate on Government policy; this is the kind of meaningless motion we have become used to from the party of protest.
“In previous meetings protests have been against the right to buy, fracking, the fire service, legal aid, bedroom tax, tax avoidance and there have been many others.
“We see no positive policies, no suggestions, no ideas, just protests. It’s frankly embarrassing.
“The taxpayers of Lancaster deserve better.
“What we could be debating is what we could do about the air pollution in Carnforth and near Our Lady’s School, the future of Skerton High School and St Leonard’s House, the Canal Corridor development, helping the Grand Theatre.
“Instead you want to issue letters to ministers claiming to represent the views of Lancaster. But our views differ from yours and we won’t give you the satisfaction.”
At this, Coun Williamson and his fellow Tories stood up and left, to slow hand-claps from the Labour contingent and cries of “Shame on you all!”
Afterwards, the remaining councillors voted through a motion to show their “disgust at the behaviour of the Tory group for leaving the chamber.
“It is an insult to democracy and the constituents they represent.”
Labour councillor James Leyshon said: “I think these cuts will punish the success of Lancashire for having outstanding police.
“I want to shout it from the rooftops the effect this is going to have and it’s a shame the Tory group don’t feel the same about representing their residents.”
His colleague Darren Clifford said: “I think it’s tragic that the Tories don’t make the connection between national cuts and the local area, in the same way as the USA doesn’t make the connection between guns and gun crime.
“All this from the self-proclaimed party of law and order. This government is soft on crime and soft on the causes of crime and this council should say so.”
A vote was taken of the remaining councillors and the motion to write to Theresa May, while also lobbying MPs and government ministers about police cuts, was passed.