David v Goliath One man's battle to expose the car finance scandal

Marcus Johnson never thought he would be rushing to a car park during a family holiday in Minehead to discuss a ruling by the highest court in the UK. But the 35-year-old factory worker from Cwmbran in south Wales also had little idea that a loan he took out in 2017 to buy a secondhand Suzuki Swift would place him at the heart of a David v Goliath battle.

- Kalyeena Makortoff

His case would go on to expose egregious commission practices in the car finance market and trigger a compensation scheme that could cost some of the UK's largest banks and specialist lenders up to £18bn.

"I thought it would be like when you did those PPI claim forms: you were just going to get a few pounds in the bank in a month or two. That's what I expected this to be," Johnson told the Guardian. "I had no idea it would turn into what it has today; I had no idea the impact it would have."

What started as interest in a Facebook advert about potential mis-selling of car loans led to a three-and-a-half-year legal battle escalating to the UK's supreme court. On Friday, Johnson's case was the only one of three consumer complaints left standing, with supreme court judges concerned about his "unfair" treatment by car lenders.

That was due in part to the size of the commission that the lender paid to the car dealer - a quarter of the Suzuki's near-£6,500 price tag - as well as a failure to disclose that a single lender, in this case South Africa's FirstRand, was given first dibs on the contract, rather than it being taken to a panel of lenders to secure the best deal.