I don't know quite how they did it, but the directors of MG Rover seem to have run into every complicated tax rule going.

First they had issues over Dextra. The Dextra decision disallowed the deduction of Employee Benefit Trust payments against profits. It also meant, in a less well noticed development, that payments from close companies hit with these charges would also pay an IHT bill.

The Phoenix four picked up not one, but both of these problems.

Now it emerges the intra-group loans could be challenged under thin cap transfer pricing rules, which prevent loans within groups being used to essentially limit tax bills, where such loans are not provided at arm's length.

It seems likely that the books, obviously made more interesting by virtue of the car company's collapse (which itself occasioned a controversial 'tax holiday'), will be a perfect case study for corporate tax lecturers for years to come.