On appeal, Patten LJ found that the Recorder had erred in his analysis of the meeting of 19/5/11. It was not possible at common law to revoke the NTQ, the professionals present at the meeting could not be described as M’s agents from the point of view of the grant of a new tenancy and it was clear from the council’s witness evidence that the council was doing nothing more than staying its hand. Once M returned to prison, he was in breach of the condition on which proceedings were stayed. From 19/5/11 onwards, M was no more than a ‘tolerated trespasser.’
Although this is a local authority possession case and involves an Article 8 defence which isn’t applicable to landlords in this particular context, it does contain a useful reminder about the common law position that, once served, a notice to quit cannot simply be withdrawn (see para 30 of the decision – Fareham BC v Miller  EWCA Civ 159) " As a matter of law it was impossible for the Council to revoke the notice to quit. Once served it was effective to determine the tenancy according it its terms. Even if the Council had made an irrevocable decision not to rely on the notice the tenancy would still have come to an end: see Tayleur v Wildin (1868) LR 3 Ex 303 ". This principle equally applies to a tenants notice to quit once served by a tenant.
Source: nearlylegal blog