If a tax return was filed in good faith several years ago, with full details of the calculation for the ER claim and then subsequently (a year or so later) HMRC won a case with another taxpayer which, if applied to your scenario, would mean that you should not have claimed ER either, would you amend the previous return? The case was in the upper tribunal and won't be appealed.
The accountant who filed the original return is adamant that the taxpayer should re-file his return (having just discovered the case). The gain is actually c 6 years ago now, so all well in the past.
Thanks for your input.