Gay rights activists and members of the Scottish Socialist party are to travel on buses in several Scottish cities today in protest at the treatment of a gay couple on a bus earlier this month.

Same-sex couples will hold hug-ins on Stagecoach buses in Dundee, Glasgow and Edinburgh. In Aberdeenshire protestors will join the couple in recreating their journey.

Altogether around 20 couples are expected to take part in the protest.

Steven Black, 16, and Mark Craig, 19, were travelling on the bus from Aberdeen to Old-meldrum, Aberdeenshire. The route is operated by Stagecoach.

The two gay teenagers were threatened with ejection from a bus and then made to sit separately after a fellow passenger complained about their behaviour.

Mr Black claims that he merely had his arm across Mr Craig’s shoulder. Stagecoach remains unapologetic about the incident, and backed the actions of the driver.

This morning a spokesperson for Grampian police told PinkNews.co.uk that an investigation is ongoing after a member of the public complained, but refused to reveal what the investigation focuses on.

Nick Henderson, LGBT spokesperson for the Scottish Socialist party, told PinkNews.co.uk:

“It is absolutely shocking that paying customers are asked to leave a bus for showing their affection.

“It is discrimination of the worst sort. It is only because they are gay – straight couples do this sort of thing all the time.”

Steven Stewart, director of corporate communications for the Stagecoach group, last week told PinkNews.co.uk that the company has carried out a thorough investigation into this complaint.

“This has involved interviewing the driver and reviewing CCTV footage from the vehicle,” he said.

“It is clear that the driver warned two passengers about the nature of their behaviour following a complaint from a fellow passenger.

“We are 100% satisfied that the driver acted professionally at all times.”

He accused the media and members of the public who have complained about the incident of not knowing the full facts of the case.

Stagecoach is part-owned by one of Scotland’s most notorious opponents of gay equality, Brian Souter.

In 2000 Mr Souter, an evangelical Christian, donated half a million pounds to a campaign in Scotland to uphold Section 28, which banned the “promotion of homosexuality” in schools.

He cited his religious beliefs as justification for his actions, insisting he is not homophobic.

Mr Souter is a member of the Church of the Nazarene, a Methodist sect. In 2000, he funded a “poll” of Scottish voters, sending out nearly four million ballot papers on the repeal of Section 28. The campaign failed in its objective.

The Stagecoach Group bus and train operating company is the second-largest in the UK with 16% of the bus market and 11% of the rail market.