Theresa May has enjoyed the longest opinion poll 'honeymoon' of any Conservative prime minister since the 1950s, new research has found.

Mrs May's premiership reaches the six-month mark on Friday, during which time her party has opened up an average poll lead over Labour of 14 points.

No Tory government in modern times has been in such a commanding position at this stage of a prime minister's time in office.

But pollsters have warned that the party's performance is more a reflection of Labour weakness than Tory strength, and could crumble if Brexit negotiations run into difficulty.

The Press Association has analysed the poll ratings for every government of the past 60 years precisely six months into the term of a new prime minister.

Only one government of any political colour has beaten Mrs May's current rating: the Labour administration led by Tony Blair, which had a colossal 29-point lead in the polls six months after Mr Blair took office in 1997.

By contrast, Margaret Thatcher's government was an average of five points behind in the polls, while John Major was six points down.

The Tories were one point ahead of Labour when David Cameron reached the six-month mark.

Theresa May's bumper honeymoon might not be entirely due to the public's rosy view of her or her government, however.

Martin Boon, director of research at the polling company ICM, said the current poll figures "are as much to do with the shipwrecked state of the opposition as the new occupant of 10 Downing Street".

He told the Press Association: "Despite perceived confusion over Brexit, policy inactivity and the lack of personal mandate, the Prime Minister can get away with most things largely because she's not Jeremy Corbyn.

"Any objective analysis of Theresa May's succession and subsequent performance would hardly qualify her initial six months as an outstanding and historic example of a government at the height of its powers."

On the plight of Labour, he added: "Pollsters are currently engaged in a game of Play Your Cards Right, with each of us shouter 'lower' as we reveal the party's latest vote share. It's 24% as it stands, but who would be surprised if it edged ever closer to a calamitous 20%?"

Anthony Wells, a director of polling for YouGov, said Mrs May's poll success is highly unusual for having lasted this long.

"Honeymoon periods for new prime ministers are traditionally two to three months," he said.

"Poll leads of 12, 14, even 17 points are particularly rare for a leader who hasn't taken over at a general election.

"With the newspapers full of the NHS in crisis, and with mixed messages on the economy, you would have thought the honeymoon would have faded by now.

"Theresa May has been lucky in not having a strong opposition party, but the poll ratings might fall once Brexit negotiations begin - especially if the public starts to think she is either giving away too much or not being ambitious enough."