ON a campaign visit to Possilpark, Glasgow earlier this month Keir Starmer and Anas Sarwar emphatically rejected any prospect of Labour working in a coalition with the SNP at a local or national level in the future.

The UK and Scottish Labour leaders were adamant there would be no deals with Nicola Sturgeon's party either after the May 5 vote or following a UK general election.

Susan Aitken, the Glasgow city council's SNP leader, had the day before told The Herald she thought Labour were being "very foolish" by ruling out alliances with the SNP.

While the SNP chief in Scotland's largest city did not elaborate why she thought that was the case, a look at the make-up of Scotland's local authorities may help to explain why.

READ MORE: Anas Sarwar criticised by council Labour chief over no deals with SNP

Currently, the SNP and Labour are coalition partners in six of Scotland's 32 local authorities - Edinburgh, East Renfrewshire, Stirling, Dumfries and Galloway, South Ayrshire and Fife, while Labour and the Tories also jointly run the administration in Aberdeen.

So by ruling out forming coalitions again with the SNP and Tories in these local authorities Labour could be opting to relinquish power in seven areas and running fewer councils than in 2017, despite winning more votes and overtaking the Tories, as polling suggests.

The Herald:

Adam McVey (SNP), left, and Cammy Day (Labour) sign a coalition agreement at the City Chambers six weeks of negotiation on June 16, 2017. Pic Gordon Terris/The Herald.

Indeed, 18 of Scotland's councils are run by two or more parties working together, while no single party runs a majority administration.

Mark Diffley, an independent pollster, said the dominance of coalitions and the rarity of one party in control in local government has much to do with the voting system for council elections.

The single transferable vote (STV) system used in council elections is a form of proportional representation which sees voters number a list of candidates. Their favourite as number one, their second favourite number two, and so on. Voters can put numbers next to as many or as few candidates as they like. Parties will often stand more than one candidate in each area.

READ MORE: Susan Aitken: Labour are very foolish to rule out a deal with the SNP

To get elected, a candidate needs a set amount of votes, known as the quota. The people counting the votes work out the quota based on the number of vacancies and the number of votes cast.

Once the counting has finished, any candidate who has more number ones than the quota is elected. But, rather than ignore extra votes a candidate received after the amount they need to win, these votes move to each voter’s second favourite candidate.

If no one reaches the quota, then the people counting the vote remove the least popular candidate. People who voted for them have their votes moved to their second favourite candidate. This process continues until every vacancy is filled.

"Advocates of the STV system would argue it is fairer as it gives a more accurate picture of what voters are thinking," said Mr Diffley.

"One of the main criticism of the first past the post system is that the majority of votes are wasted, so a candidate could win on 35% per cent of the votes in the area and win which means the politician is representing an area even though the majority hasn't vote for him or her."

He added that extrapolating to a council wide basis the STV system means it is harder for one party to get an overall majority because it is very rare for a single party to get more than 50 per cent of votes. To win on STV a party would need to get over 50 per cent of votes and both candidates first, second and third.

However, often voters mix up their party choices and "share their votes around" when they rank them, Mr Diffley added.

"The STV proportional representation system is one of the reasons why there are so many coalitions in local government - another being a high number of independent candidates standing too.

"There is much more of a tradition of independent candidates standing than at a national level."

But why then is Labour apparently so keen to stress that it is opposed to a forming new coalitions with the SNP?

Diffley said the wariness is political and much to do with the shadow of 2015 general election campaign and defeat which still hangs over the party.

Ahead of the vote the then party leader Ed Miliband failed to rule out a post election alliance with other parties - a stance seized on by the Conservatives who immediately plastered giant posters all over the UK of the Labour chief in Alex Salmond's pocket in a bid to scare voters in England and Pro-Union supporters in Scotland.

"It is said that this was one of the reasons for Labour's defeat," said Mr Diffley.

"The message from the Conservatives was vote Labour, get SNP and another referendum. And although you can argue that there is a very big difference between that and whether for example Highland Council has a Labour/SNP partnership [and local council elections shouldn't be about constitutional issues] Anas Sarwar is worried about sending out a message that could be a gift to the Tories."

At a local level, though Mr Sarwar's and Mr Starmer's stance has its critics among Labour council chiefs.

As the Herald reported last week Elaine Murray, the Labour council leader of the Labour/SNP coalition which runs Dumfries and Galloway Council, said the arrangement has worked well.

She said the two parties were able to set aside their differences over the constitution and find a common policy platform to deliver.

Councillor Murray said the joint administration had taken steps to grow the local economy, supporting small and medium sized businesses and improving the level of skills within the local workforce.

She added too that goals had been met to roll out household recycling scheme across the region, lobby the Scottish Government to extend 80% funding to include smaller flood prevention schemes.

In terms of support for children, she said the council had developed free breakfast clubs in every primary school across Dumfries and

Galloway; delivered 1140 hours childcare for every eligible preschool child and raised school attainment.

Ruling out a coalition with the SNP, could let the Tories in as a minority administration, Councillor Murray warned.

"The Conservatives are the largest party, so the alternatives are a minority Conservative administration... or some form of partnership between Labour and the SNP," she said.

"If they were ideological Tories they could cut a lot of the services. For example we have chosen to invest £1million a year in anti-poverty measures such as the holiday hunger programmes [for school pupils]. It could well be, that the Tories would chose not to do that and spend the money elsewhere."

In Edinburgh city council, where Labour and the SNP have also been in coalition since 2017, the SNP group leader and council leader Adam McVey, is again open to a coalition with the other main parties, apart from the Conservatives.

Like Councillor Murray in Dumfries and Galloway, he said the SNP/Labour coalition has been successful.

"Both our parties in 2017 put aside our party interests and worked together to get the best for Edinburgh. Our manifestos worked well together and we shared a view of a fairer, greener Edinburgh with better public services for residents. We knew that working together, and with other parties, was the only way we'd be able to make progress on these key issues," he said.

"The last five years has given the Capital a strong direction and build solid foundations for more reform. Both parties have been able to use their experience and ideas to deliver for the city and none more so than when we had to work together through the pandemic to keep people safe, and lifeline services running."

Edinburgh Labour group leader and depute council leader Cammy Day, was more coy though appeared to suggest there could yet be discussions with the SNP should the Labour leadership soften its stance post May 5.

"We are currently campaigning to win as many seats as we can in Edinburgh, to run or influence the next administration and await guidance on post election discussions," he said.