The speech followed last month's surprise Pre-Budget Report announcement that from next April company owners who currently enjoy a 10 per cent rate of tax relief on the proceeds of their asset disposals would see it rise to a flat rate of 18 per cent.

The move would significantly impact private owners of dealerships and repair garages who are currently planning on exiting from the sector or selling up to retire.

Under the current rules they qualify for tax relief on their capital gains at the lower rate. Speaking at last week's conference Darling admitted his move was unpopular but claimed it was “right and fair” and motivated by a need to clarify the existing regime. “Simplification of the tax system is important because complexity brings increased costs. I know that my proposals to introduce a single rate of CGT have been controversial. That was inevitable,” he said. “We are working with the CBI and other business organisations to listen to what you have to say. I expect to publish final proposals in the next three weeks.” Darling's speech appeared to do little to appease business leaders with the CBI's director general Richard Lambert saying that the proposals would need to revised to avoid a “cry of rage” from businesses.