A lengthy report produced by the UK200Group – which represents small and mid-tier firms – revealed that neither the Remain nor the Leave campaigns were certain of a cut-off point for cases going to the court, nor of what would become of cases already before it.

The Remain camp simply said the UK’s relationship with the ECJ ‘would depend on the kind of future relationship Britain would have with the EU’.

For its part, Leave said it ‘would be for the UK and the EU to determine the cut off’.  

It added: ‘After we vote leave, we would expect parliament to legislate to amend or repeal the 1972 Act which gives the European Court control over our law.

‘However, the referendum will have no legal consequences save for the certification of the result by the chief counting officer. After the UK voted to leave, it would therefore initially continue to be a member of all the EU institutions under the EU treaties with the voting rights of a full member.’

Cases before the ECJ have been known to take years to conclude, and there are currently several significant live cases that could conceivably be affected, including UBS and Deutsche Bank’s challenge to HMRC over its bonus scheme.

The case of Bridport & West Dorset Golf Club and its long-running VAT dispute with HMRC could also find itself caught up, while the Glasgow Rangers FC oldco’s long-running employee benefit trust spat could also be in the crossfire, although it will be considered by the Supreme Court in 2017.