An academic study showing support for Kezia Dugdale staying on as Scottish Labour leader was based on focus groups and interviews involving just 53 people.

The Sunday Herald can also reveal the party has about 22,000 members, meaning less than 0.5% of the Labour family took part in the exercise.

Dugdale won her party’s leadership last year after an easy victory over rival Ken Macintosh that saw her win over 70 per cent of the vote. However, a woeful Holyrood election result and tensions with UK leader Jeremy Corbyn have created internal problems for her.

Vince Mills, a long-term party member who is vice-chair of the pro-Corbyn Momentum group in Scotland, has called on Dugdale to quit if next year’s council election go badly.

Days after Mills’ intervention, newspapers reported findings of a study commissioned by Scottish Labour and carried out by academics at Bath University.

The Scottish Labour Membership Study, based on fieldwork in cities across the country, was aimed at identifying key trends and feelings within the party.

It was reported in the media that seven focus groups of between 10 and 15 new and long-term party members were held, as well as 13 interviews with key party figures.

An extract of the report stated: “There was universal agreement Kezia should remain leader for the next 10 years.”

However, a Scottish Labour spokesman later confirmed to this newspaper that around forty people took part in the focus groups, which alongside the interviews took the participation rate to 53.

He added that the majority of the focus groups were held in Edinburgh – Dugdale’s political heartland – and every MSP was invited to take part in the study.

Although the exercise will provide valuable insights into the party, the low number of people surveyed will inevitably raise questions about how representative it was of the membership.

In late 2014, Labour had around 13,500 members north of the border. At her leadership launch last year in Edinburgh, Dugdale confirmed that the number had risen to around 15,500.

Since that day, two UK leadership contests have taken place and both triggered an influx of new members to the Scottish party. It is now understood the total is closer to 22,000, a significant jump when compared to the 2014 referendum level.

This means that around one in 400 Scottish Labour members took part in a survey subsequently hailed as good news for Dugdale’s leadership.

Dr Sophie Whiting, one the of the academics who carried out the study, said: “This research was based upon a series of hour-long focus groups. These drew upon a sample of party members that took into account gender and geography, included new and old members, and was supplemented by interviews with key figures from across the party.

“The study's aim is to help direct a planned future large-scale quantitative survey of party members in line with methods adopted for previous research we have carried out with other British political parties."

John Lamont, the Chief Whip for the Scottish Tories, said: "This survey was hailed as evidence that Labour party members were fully behind Kezia Dugdale, but it now seems apparent that only a tiny fraction of the rank and file were even asked. The truth is that Labour is still hopelessly divided.”

A Scottish Labour source said: "This was a major research project by a leading university, and any attempt to tarnish the reputation of the university or the researchers involved is insulting and represents a gross misunderstanding of how this extensive work was conducted.

“It involved weeks of work by two leading lecturers in one of the world's most respected public policy research institutes. As the renowned experts involved concluded, Scottish Labour’s membership is firmly behind Kez."

A spokesperson for Scottish Labour said the study would not be published.