6. A claimant shall not be taken to be in breach of the undertaking referred to in regulation 5 if—
(a)he is prevented from continuing to comply with that undertaking by reason of any material circumstance beyond his control; or
(b)he has ceased to farm, and at least three hectares of the eligible land, or of any related less favoured area, last used by him for the grazing of animals continue to be used for the purposes of agriculture.