Speaking to the BBC, Martin said: “So in summary, on Friday, one of three things is likely to happen. First, the Supreme Court upholds the Court of Appeal ruling on commission disclosure arrangements.

“To be honest, that shakes everything up in the air, there may be political intervention, we don't know when. If not many people with car finance, virtually all of them will be due a payout but we don’t know the scale.”

If the Supreme Court decides that old cases and contracts are eligible for compensation, lenders could be set for a staggering £44billion bill.

However, there are suggestions that Chancellor Rachel Reeves could get involved and overrule the decision to protect lenders. This may have an impact on total compensation, but the Treasury has refused to “comment on speculation”.

Martin explained that if the Court of Appeals decision is rejected by the Supreme Court, drivers could receive some payouts from the Financial Conduct Authority (FCA). However, Martin warns the Supreme Court may yet pull a rabbit out of the hat so nothing is certain until the final decision is out in the open.

The Money Saving Expert added: “Second option, the Supreme Court rejects the Court of Appeal ruling in part or in full, in which case discretionary commission arrangement cases will still go ahead via the regulator as they were planned to.

“They could even launch a system where people don't have to apply to get their money back if they were mis-sold. It might just tell firms they have to pay out automatically.

“The third one is the Supreme Court comes out with something novel and we just haven't even prepared for that one. That’s my unknown unknown.”