If you thought scrappage was confusing when it was announced a month ago, who would have thought the day it went live it would suddenly become a lot more complicated.

Ford and Honda said this morning they will not be able to take part because of an unresolved and ultimately essential detail involving VAT and dealer margins.

Alarm bells began ringing almost as soon as the scrappage fanfare died down at the end of April.

It was just a few days after the plans, which had a dubious lack of detail, were revealed that the Society for Motor Manufacturers and Traders (SMMT) called the government into a meeting armed with 50 questions that needed to be answered.

A week ago, the day before the deadline for manufacturers to sign up, the SMMT said that these concerns had been answered, but discussions continued.