GSTS Pathology LLP: When do legitimate expectations end?

The recent decision in R (oao GSTS Pathology LLP & Others) v HMRC is significant in the context of taxpayers challenging decisions of HMRC by means of judicial review. It is understood to be the first time that interim relief has been granted in the form of an order restraining HMRC from collecting tax prospectively, which HMRC now considers due, whilst an appeal remains pending in the FTT regarding the correct tax treatment.