PA MediaReform UK has taken overall control of Lincolnshire County Council following Thursday’s local election.
As counting continues, they have hit the majority needed with 41 seats, currently ahead of the Conservatives in second, who have nine seats so far.
It marks a double success for the party, which earlier saw Dame Andrea Jenkyns elected as the county’s first mayor in a resounding victory.
Outgoing council leader Martin Hill, who has led the authority for 20 years, said there had been a “tidal wave of Reform crashing over us”.
Hill, who retained his Folkingham Rural seat, added: “It’s all about national politics, they had very simplistic messages.
“On the doorstep, people were saying they were fed up with both national parties.
“Immigration was a big issue and that’s what it all seemed to be about.”
All 70 seats across the county council were contested and the results showed a huge swing from the 2021 election, when the Tories secured a majority 54 seats.
East Lindsey went to Reform in its entirety, with big wins in Lincoln, Boston and South Holland.
There were also some high-profile Conservative casualties, including Colin Davie, who lost his Ingoldmells Rural seat to Reform by almost 1,000 votes.
Fellow councillors Wendy Bowkett, Daniel McNally, Patricia Bradwell and William Gray, who have decades of council experience between them, will also be leaving the chamber.
The Liberal Democrats narrowly managed to retain two seats in Gainsborough, including that of district council leader and Mayoral candidate, Trevor Young, who won by 17 votes.
Elsewhere, the Lib Dems have picked up two new seats which currently makes them the second largest party in the county.
Independent Richard Cleaver won big in Stamford West.
Analysis by Alan Webber, BBC Radio Lincolnshire political reporter
To echo the words of the UK’s Eurovision entry, “what the hell just happened” in Lincolnshire?
The answer: “A tidal wave of Reform crashing over us”.
Those are the words of Martin Hill who led Lincolnshire County Council for 20 years, but not for much longer.
He told the BBC the electoral wipe-out was the result of national problems and “easy answers” offered on the doorstep.
The Tories have controlled the authority for most of the last 50 years, and started the night with 53 out of 70 seats.
There have been some long-standing political casualties – including Colin Davie who lost his Ingoldmells Rural seat to Reform by almost a thousand votes.
In all, decades of council experience will be leaving the chamber.
The newly-elected Reform UK councillors will have to hit the ground running to adjust to the demands of managing an authority with an annual budget of £693m.
