Professor John Curtice YouTube LONDON — A poll indicating a surge in support for Scottish independence was likely the result of "sampling error," according to leading pollster John Curtice.

A BMG poll published by the Herald newspaper on Wednesday indicated a 3.5% rise in support for independence over January to 49%, with 51% opposed.

The results appeared to indicate that Theresa May's pledge to pursue a "hard" Brexit and pull Britain out of the single market had driven up support for independence in Scotland, which voted to remain in the EU by a margin of 62% to 38%.

BMG research director Dr. Michael Turner told the Herald the result showed the Brexit vote was "undoubtedly having an effect on support for the principle of independence," and pro-independence politician Alex Salmond greeted the news by tweeting: "Game on..."

Curtice, professor of politics at the University of Strathclyde, told BI that the survey was more likely the result of polling issues.

"A 3 point change is certainly the kind you could get simply from a sampling error or sampling variation," he said.

"The proposition that the UK government's stance on Brexit has shifted Scottish public opinion is not supported by the other recent poll, the Panelbase survey in the Sunday Times which had support for independence down by 1% [at 46%, with 54% opposed]."

"In the absence of any corroborating evidence, it’s a reminder that the position is close, the position has always been close — and that polls which put support for "Yes" as low as 45% may be slightly under-egging the pudding, while polls that put it at 49% may be slightly over-egging it."

He added: "I've looked at the innards of the poll to see if there's any evidence of the pattern of transfer from what people did in 2014 to what they say they'd do now, and whether it looks significantly different from previous polls.

"The answer is that it doesn't — it looks very similar. To be honest, unless we get a lot more evidence to corroborate it, I would say it is simply a reminder to the UK government that if there is a referendum, it could lose it.

"It certainly helps the Scottish government to have such a poll at this point in time, because it reminds the UK government of that risk, but I would be wary of presuming that we are seeing a significant change in the scene so far," Curtice said.