Professor Michael Thrasher, an analyst for Sky News, said: "This does put them below what the national opinion polls are now saying".
The Conservatives look set for big gains in Scotland.
The Tories have gained massive ground from the UKIP and Labour but the party has chosen to strike a note of caution to prevent its prospective MPs becoming too complacent in the general election campaign.
As expected, Labour won mayoral races in Manchester, Liverpool and Newcastle, but they were beaten in the West Midlands race, centred on Birmingham.
The party even lost control of the city council in Glasgow, Scotland's biggest city and once the staunchest of Labour strongholds.
If the price of Britain leaving the European Union is a Tory advance after taking up this patriotic cause, then it is a price Ukip is prepared to pay.
Labour remain the biggest party on Bridgend council, with 26 seats, but the Conservatives, who only had one seat, now have 11.
The Liberal Democrat results have been mixed, with some gains and some losses.
The Conservatives made sweeping advances across the United Kingdom, gaining more than 500 councillors, winning tightly-fought battles for elected mayors in the West Midlands and Tees Valley and forcing Labour into third place in its former stronghold of Scotland.
As Ukip shed 107 councillors while holding a solitary seat in Lancashire, leader Paul Nuttall said the party was "a victim of its own success" over Brexit.
The prime minister has styled herself as offering the most stable leadership to take Britain through two years of tough Brexit negotiations, and she took aim at Brussels on the eve of the local elections. Party leader Nicola Sturgeon said her party had achieved "a clear and emphatic victory".
The Tories were up on 276 seats, up 164.
Iain said: "Given the background of what happened over the last 48 hours, 382 losses, the first time an opposition has lost council seats in three consecutive years in political history, how do you come back from that?"
But the poll pain could continue as results feed through for Scotland, where Labour has been decimated by the SNP.
If Labour is looking for any good news to cling to, the BBC's election guru John Curtice has said today's figures suggest a national vote share of 38% for the Conservatives, versus 27% for Labour and 18% for Liberal Democrats - not quite the wipeout for Labour some polls have indicated. When I said we could do this - people simply didn't believe me.
"I wasn't sure if people could bring themselves to vote Conservative because we still have a mining heritage".
Elections expert John Curtice, professor of politics at Strathclyde University, said Ukip, which won 3.8 million votes at the 2015 general election, had lost "everything they've been trying to defend".