A flexile type of letting agreement that often used for short term property letting. The agreement is indefinite and continues until the one of the parties gives notice to bring the tenancy to an end.
Can occur after exchange of contracts if a purchaser wants to gain access to the property before legal completion e.g. to start the renovation etc.
Can be organised formally through the solicitors and a licence arranged between both the vendor and the buyer. The buyer might agree to pay an appropriate rate of interest on the balance of money owed for the property (i.e. the purchase price of the property less the deposit that they have already paid).