Any hopes of a "Beijing bounce" for Gordon Brown on the back of Britain's Olympic successes were dashed by the latest monthly Ipsos/Mori survey.

Twice as many electors said they would vote Tory as Labour (48 per cent to 24 per cent) at the next General Election, the biggest gap recorded since the pollsters' records began in 1977.

It is four points wider than a month ago – with Labour dropping three.

Among all the 1,005 voters polled by telephone between August 15-17, the Tories enjoyed a 14-point lead by 42 per cent to 28 per cent – with the Opposition up two on last month.

And with more than three quarters unhappy with the way the Government is running the country (76 per cent to 20 per cent), most (58 per cent) now believe David Cameron's party is ready for office.

The Tories remain well ahead on their ability to run the economy (by 38 per cent to 23 per cent), the issue considered most important by voters, 72 per cent believing things will get still worse in the next year.

And the public now has more faith in them on every aspect of policy – including education (by one point), the environment and housing (three points) – bar health on which Labour is ahead by three.

Ipsos Mori's August Political Monitor found 71 per cent dissatisfied with Prime Minister Gordon Brown's performance, including 39 per cent of Labour supporters.

Mr Cameron enjoyed a 51 per cent approval rating – supported by all but 14 per cent of his party's supporters – and is considered the more capable to lead the country out of the present economic situation by 50 per cent to 29 per cent.

The Liberal Democrats were up one on 16 per cent among those certain to vote, but down one from 18 per cent to 17 per cent among all those stating a preference.

Ipsos Mori said its previous low score for Labour was 27 per cent and it believed the 24-point gap was the biggest seen in a telephone-based poll.