CAS has been campaigning on the issue since last year, when the It’s Not Fine campaign found that many Scots are being charged huge amounts of money for very short over-stays.

It also found that private car parks often don’t have clear signage setting out their fees, and that many firms were using aggressive and misleading tactics when pursuing debts.

The consumer campaigners commissioned Mark Lindsay QC to give his opinion on the position in Scots law to private parking charges.

Since CAS started the campaign it has seen massive increases in the number of Scots seeking advice on the issue:

The number of people coming into a Scottish CAB with a private parking issue has increased by 45% in the last year.

On its self-help website, the number of people seeking advice on the issue was 4,000 in February 2013, but had risen to 25,000 in March 2015.

The organisation’s consumer helpline took just under 60 calls about the issue in the first quarter of year 2012/13. By the final quarter of year 2014/15 the figure was over 160.

Now, the expert legal opinion commissioned by CAS has stated that consumers can challenge tickets issued by private car parks, and for the first time has set out the grounds on which they can do so.

Publishing that legal opinion today, CAS head of policy Susan McPhee said: “In recent years we have seen a huge increase in the numbers of people seeking advice after being charged unfairly by private car parks. It is one of the most common consumer issues that we see.

“Last year we launched a major campaign to highlight the issues and to urge people to fight unfair charges. However the problem was that the legal situation has ways been unclear in Scotland, because it has never been defined. So that’s why we commissioned a formal legal opinion.

“Now for the first time ever in Scotland, we have that legal opinion. And it states clearly that people can challenge private parking fees on two specific grounds: the size of the charge and whether the charges were adequately displayed in the car park.

“This is an important milestone in the campaign for fairer parking charges in Scotland. Legally, consumers now have a clear guide to how they can get redress for unfair treatment, and car parking firms know exactly what they are required to do in managing their business fairly and legally.”