The survey '“ arranged by Tory peer Lord Ashcroft '“ made headlines around the UK in June when its results were unveiled, saying that the 44% of respondents would back Irish reunification in a border poll.
The figure was only slightly below the 47% who said they would opt to keep the Union, and is double the pro-nationalist figure given in some other recent public opinion surveys (all the results are set out side-by-side below).
The results may well be raised at a crunch government meeting today in Chequers '“ the prime minister's country residence '“ when the government will congregate to discuss Brexit, including the future of Northern Ireland.
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Lord Ashcroft Polls '“ the name which the Conservative figure uses for his survey work '“ said it had done the 'questionnaire writing, analysis and interpretation of the results'.
But when it comes to who did the fieldwork '“ including sourcing people to take part in the survey in the first place '“ it only said that 'fieldwork/data collection was outsourced to a reputable external agency', but not who it was.
It said 'we don't usually name our fieldwork suppliers', and would only say they are members of the British Polling Council, an 18-strong industry body.
It is common for survey firms to use other companies in this way '“ getting them to go and do the actual interviews or collect raw data which they later analyse themselves.
The British Polling Council has said there is nothing unusual or untoward in not disclosing the name of a firm which carries out fieldwork.
However, Graham Gudgin, a Cambridge academic and chief economic advisor to think tank Policy Exchange, said while some may 'regard this secrecy as standard practice', it is 'clearly unsatisfactory in the fraught political situation of Northern Ireland where opinion polls play a role in the constitutional process'.
He added: 'Theresa May has already cited support for Irish unity as a factor in avoiding a hard border in Ireland and it would not be surprising if these poll results featured in the Chequers discussions on the future customs arrangements for the UK including Northern Ireland.'
And Jim Allister, TUV MLA and Brexiteer, said in the interests of transparency it was 'reasonable' to know.
He said any opinion polls are open to question, adding: 'I think that's then compounded if they are secretive about the source of how it was done and who it was done by.
'I think Lord Ashcroft's poll, by keeping secret, and therefore free from scrutiny, who was involved, by doing that he undermines his own poll and his results '“ which I don't accept for one moment anyway.'
The Ashcroft survey was carried out via the internet, from May 24 to May 28.
Initially it looked like YouGov '“ a major worldwide market research firm '“ did the fieldwork.
The data spreadsheet underpinning the Ashcroft survey included a page saying 'this spreadsheet contains survey data collected and analysed by YouGov plc' and 'all figures, unless otherwise stated, are from YouGov Plc'. It was headed with YouGov's logo, and the digital file marked as copyright of YouGov.
But when the News Letter got in touch with YouGov, it responded that it did not in fact run the fieldwork at all.
A YouGov spokesman said they had merely offered the use of 'our tools/software to run the tables for Lord Ashcroft Polls', and the references to the firm had been left on the spreadsheet by mistake.
Whilst two face-to-face studies of public opinion released this year on the same border poll question (one of 1,012 people done by Queen's University Belfast and one of 1,203 people by the Northern Ireland Life and Times Survey) showed pro-united Ireland support running at 21% and 22% respectively, a Northern Irish agency called LucidTalk did recently produce a survey with results as similarly high as the Ashcroft one.
Like the Ashcroft one, it was conducted online. It was run from May 4 to May 10, and had been done by LucidTalk for YouGov and the BBC.
This survey involved contacting roughly 10,500 adults who belong to the '˜LucidTalk Opinion Panel' '“ an existing pool of people willing to take part in surveys. In all, 1,336 responses were considered.
The results were that 45% would stay in the UK in the event of a border poll; 42.1% would join the Republic; 12.7% were undecided; and 0.2% said they would spoil their vote or not vote at all.
The Ashcroft survey involved 1,666 adults.
They were drawn from a 'larger panel of people who have agreed to take part in polls and surveys', Lord Ashcroft Polls said, most of whom had already done other surveys previously.
Once responses from these 1,666 people were received, they were '˜weighted' to make them representative of the population at large.
For example, nestled in the Ashcroft survey data is the fact that a hugely disproportionate number of Alliance voters took part '“ 362. By contrast, there were only 227 DUP voters.
Lord Ashcroft Polls said 'it is quite normal for some groups (eg, by age, region, party support or other factors) to be over or under-represented in the raw sample of a survey' and that 'Alliance voters were '˜down-weighted' and DUP voters '˜up-weighted' to reflect the NI population' when the results were processed.
Such weighting 'is the standard way of conducting online surveys' it said.
The full Ashcroft survey results? In all, 49% said they would vote to stay in the UK if a border poll were held tomorrow; 44% said they would vote to leave; and 7% said they did not know (it did not give people an option of saying they would not vote at all).
Given that these results in the Ashcroft survey roughly mirrored those of the LucidTalk survey, and they were both done in a similar fashion (conducted online using an existing pool of candidates), LucidTalk's boss Bill White was asked if it was his firm which had carried out the fieldwork for Lord Ashcroft.
He responded that Lord Ashcroft Polls 'use a whole range of companies'.
As to whether he was involved, he said: 'I can't comment on that. You'd have to talk to Lord Ashcroft Polling about that.
'It's like anything. It's client confidentiality. I can't make any comment one way or the other.'
LucidTalk had announced itself online that it was running a survey from May 24 to 28 on 'Brexit issues' for a 'major UK and international polling company' '“ the same dates Lord Ashcroft's survey (called '˜Brexit, The Border And The Union') was conducted.
When this was put to him, Mr White said: 'But I can't comment on that. I know what you're trying to do. They use a range of companies.'
In general terms, when it comes to the difference between LucidTalk's results and those of Queen's and the NI Life and Times Survey, he said the surveys are 'in the same ball park' when it came to showing support for the Union (see full figures in Analysis, top right).
However, he said face-to-face surveys, like the Queen's and Life and Times ones, often throw up different results to online ones. He said 'because of our online methodology, we draw out more of the shy pro-united Ireland voters'.
This is borne out in the fact that the LucidTalk poll's measurement of 42.1% for a united Ireland more closely resembles actual ballot box results come election time, he added.
If the support for a united Ireland really was as low as the NI Life and Times and Queen's surveys suggested, then he said 'that would mean in a real live border poll over 150,000 regular Sinn Fein/SDLP voters would have to vote pro NI-in-UK '“ which doesn't pass a common sense test!'
THE POLLS SIDE-BY-SIDE:
Ashcroft: 49% would vote to stay in the UK if a border poll were held tomorrow; 44% would vote to leave; 7% said they did not know (it did not give people an option of saying they would not vote at all)
LucidTalk: 45% stay in the UK; 42.1% join united Ireland; 12.7% were undecided; and 0.2% said they would spoil their vote or not vote at all
Queen's: 50.3% stay in the UK, 21.1% join united Ireland, 18.9% do not know, and 9.7% would not vote.
NI Life and Times: 55% stay in the UK; 22% join united Ireland; 10% do not know; and 12% would not vote.
It is no exaggeration to say that some day nothing less than the fate of the Union may hinge on the mechanics of how opinion polls work.
A reunification referendum is likely to be a growing nationalist demand in coming years, and so far this year different attempts to gauge public mood on the matter have come up with quite different results.
The Queen's University and NI Life and Times Survey (a long-running project set up by both Queen's and the University of Ulster) involved employing others '“ Ipsos MORI and a Belfast firm called Perceptive Insight, respectively '“ to physically visit random houses and gather data face-to-face.
And whilst the online LucidTalk and Ashcroft polls found pro-Union support of 45% and 49%, not far off the two face-to-face surveys, their pro-united Ireland readings were about double those of the results above.
Given Lord Ashcroft's stature (he is a former deputy chairman of the Conservatives), many in the government may be inclined to focus on his figures, and be gripped with trepidation at the thought that if a border poll were to be called the results could be nearly as close as the Brexit vote.
The issue's importance cannot be stressed enough.
Given that evidence of a support for re-unification is a pre-requisite for the government calling a border poll, looking deeply at these surveys of public opinion '“ and how they are done '“ is crucial.