"More than two out of three of Britain's voters no longer trust the Tories to provide their local public services," Simon Hughes, Liberal Democrat urban affairs spokesman, said.
It was unprecedented for the governing party to have so little support at local level, he said.
The Liberal Democrats said the number of Conservative councillors across England had dropped by 18 per cent since 1979 - from more than half of councillors to a third in 1994.
During that time, representation by Liberal Democrats and their predecessors in England had risen by almost the same amount, 17 per cent - from 4 per cent to 21per cent, Mr Hughes said. Labour councillors were up by 12 per cent.
The most dramatic changes were in the shire counties, where Conservative representation had halved from 62 per cent to 31per cent. Labour now held 37 per cent of shire seats, up from 22 per cent in 1979, while Liberal Democrats had risen from 2 per cent to 28 per cent.