The House of Commons Public Accouns Committee has tried to find out of H M Revenue & Customs resolve tax disptes appropriately. But as they have reported:
The Department did not answer some of our specific questions on tax disputes on the grounds that it has a legal duty not to disclose taxpayer details, except in certain limited circumstances.58 This applies to all taxpayers, whether they are an individual or a publicly quoted company. This inevitably makes it difficult to obtain assurance that the Department resolves tax disputes appropriately.
So the answer is "who knows?".
Which justifies all the concerns many have on cases such as Vodafone.