It has been the experience of the founders of LTAG, Albert May and David Rangeley, that HMRC are not always correct. Indeed on as many as seven prior occasions Albert and David have managed to settle with HMRC cases some of which had been ongoing for almost 15 years.
By and large the settlements have been through amicable settlements that HMRC themselves professed were extremely professionally managed including to their own satisfaction.
As tax-payers one should not feel that all options are closed when presented with a tax bill that you feel is unjust. LTAG has been created for this very purpose – HMRC like other entities have limitations on what they can do and for how long.