If a shareholder in a private company has gifted shares, continues as a director and receives director’s fees, but in say 10 years time his involvement in the company affairs Has reduced to a minimal amount, do hmrc argue that there is then a GWROB, even if when the gift was made the level of fees was at that time a reasonable commercial arrangement and not a GWROB?
Despite the decision in Oakes  HMRC do not in your scenario seem to automatically argue a GWR applies.
The key seems to be whether the fees are in any way affected by the gift of the shares or whether the fees are simply a continuation of the level of fees pre the gift (assuming arm’s length in nature).
However, if in due course the work carried out significantly reduces then HMRC may well argue for a GWR.
See IHTM para 14334 plus for some possible helpful commentary.