A former Labour Cabinet minister says pollsters "skewed the election campaign" and future surveys need to be adjusted accordingly after a post-mortem into how the industry failed to predict a Tory general election victory.
Ben Bradshaw, one of just a few Labour MPs to increase their majority in May, criticised the quality of the polling used and argues every poll published between now and the 2020 election should subtract 3% from the Labour vote and add 3% to the Tory share.
David Cameron and his wife Samantha Cameron arrive at Downing Street on May 8
An independent inquiry commissioned by the British Polling Council found that the failure was due to a "systematic over-representation of Labour voters and under-representation of Conservative voters".
It also could not rule out the possibility of "herding" among pollsters not wanting to be out of line with their rivals. But it found evidence of a late swing to the Tories was inconsistent.
Despite polls suggesting a neck-and-neck race, the Conservatives won with a comfortable 6.5% victory margin on May 7.
Mr Bradshaw, MP for Exeter in Devon, well beyond Labour's heartlands, suggested pollsters should still face tough questions.
He told The Huffington Post UK it was "pathetic" pollsters, which use randoms samples of voters, were not willing to pay for more accurate polling. Most use political polls as a loss-leader to generate more lucrative work from industry.
The former Culture Secretary also thinks the newspapers and broadcasters that commission polls should do fewer and pay more for accurate data.
He also revealed few Labour MPs were aware of the party's private polling "beyond Ed Miliband's inner-circle" that suggested they were trailing.
Polling indicating Labour defeat was only shared within Ed Miliband's team
Mr Bradshaw said: "This failure by the polling organisations seriously skewed the election campaign. Instead of focussing on a probable Tory majority Government the whole media narrative was about the likelihood of a hung Parliament.
"The pollsters complain it would be too expensive to do more accurate sampling. This is pathetic. If they won't spend what is required the produce accurate forecasts we basically need to subtract 3% from Labour and add 3% to the Tories in every poll published between now and the 2020 election.
"But media organisations that commission polls are also guilty. They should commission fewer, but spend more on them, so they're more accurate."
He added: "Only one person comes out of this well - James Morris who did the private polling for the Labour leadership, which was accurate, but tragically not shared outside Ed Miliband's inner circle. Even most Labour MPs were unaware of it."