P granted D a lease for such time as exists until P (a council) decides to broaden the road at 2 months notice. Rent was charged annually. In the end, they decided not to broaden the road, and both assigned their rights to P2 and D2 respectively. When P2 purported to give notice to D2 to determine the lease, D2 claimed that the lease could only be determined if the road was to be widened. HL held that since leases have to be of certain duration, the originally granted lease was invalid (though it would have been valid if granted for, say, 5 years, but capable of being determined by the land lord before this time for road widening etc). However in taking possession and paying rent, a periodic yearly lease had been set up in accordance with the terms contained on the memoranda between the parties and since yearly tenancies are terminable on 6 months notice. Hence the lease could be terminated even though there was no widening of the road.
Lord Templeman: A yearly tenancy is sufficiently certain in length since either party can end it on 6 months notice. The clause saying that notice cannot be given until the roads are to be broadened is incompatible with the yearly lease and is to be ignored, since it would make the lease uncertain in length (could render the tenancy indefinite).