"I accept Mr Graves’ evidence when he said "
“Mrs Graves was prepared to leave provided .., as her final proposal,£6,250 of her deposit was paid back and in those circumstances, she would be out by31 July 2005 .”
"Logically, before one can turn to the rules as to mistake, whether at common law or in equity, one must first determine whether the contract itself, by express or implied condition precedent or otherwise, provides who bears the risk of the relevant mistake. It is at this hurdle that many pleas of mistake will either fail or prove to have been unnecessary. Only if the contract is silent on the point, is there scope for invoking mistake."
“Where a fundamental assumption upon which an agreement is made proves to be mistaken, it is not realistic to ask whether the parties impliedly agreed that in those circumstances the contract would not be binding. The avoidance of a contract on the ground of common mistake results from a rule of law under which, if it transpires that one or both of the parties have agreed to do something which it is impossible to perform, no obligation arises out of that agreement.”
“Frustration of a contract takes place when there supervenes an event (without the default of either party and for which the contract makes no provision) which so significantly changes the nature (not merely the expense or onerousness) of the outstanding contractual rights and/or obligations from what the parties could reasonably have contemplated at the time of its execution that it would be unjust to hold them to the literal sense of its stipulations in the new circumstances; in such case the law declares both parties to be discharged from further performance.”
“74. In considering whether performance of the contract is impossible, it is necessary to identify what it is that the parties agreed would be performed. This involves looking not only at the express terms, but at any implications that may arise out of the surrounding circumstances. In some cases it will be possible to identify details of the "contractual adventure" which go beyond the terms that are expressly spelt out, in others it will not. … 82. Where it is possible to perform the letter of the contract, but it is alleged that there was a common mistake in relation to a fundamental assumption which renders performance of the essence of the obligation impossible, it will be necessary, by construing the contract in the light of all the material circumstances to decide whether this is indeed the case. In performing this exercise, the test advanced by Diplock LJ, applicable alike to both frustration and fundamental breach, in Hong Kong Fir Shipping Ltd Co v Kawasaki Kisen Kaisha Ltd[1962] 2 QB 26 at 65-66 can be of assistance.”
“Whenever it is to be inferred from the terms of a contract or its surrounding circumstances, that the consensus has been reached on the basis of a particular contractual assumption, and that assumption is not true, the contract is avoided: i.e. it is void ab initio if the assumption is of present fact and it ceases to bind if the assumption is of future fact”
“I think few would demur to this statement, but its value depends upon the meaning of “a contractual assumption” and also upon the true meaning to be attached to “basis”, a metaphor which may mislead…. Various words are to be found to define the state of things which made a condition. “In the contemplation of both parties fundamental to the continued validity of the contract” “a foundation essential to its existence”, “a fundamental reason for making it”, are phrases to be found in the important judgment of Scrutton LJ in the present case. The first two phrases appear to me to be unexceptionable. They cover the case of a contract to serve in a particular place, the existence of which is fundamental to the service, or to procure the services of a professional vocalist whose continued health is essential to performance. But “a fundamental reason for making the contract” may, with respect be misleading. The reason of one party only is presumably not intended, but in the cases I have suggested above, the sale of a horse or of a picture, it might be said that the fundamental reason for making the contract was the belief of both parties that the horse was sound or the picture was an old master, yet in neither case would the condition, as I think, exist. Nothing is more dangerous than to allow oneself the liberty to construct for the parties contracts which they have not in terms made by importing implications which would appear to make the contract more business like or more just. The implications to be made are to be no more than are necessary for giving business efficacy to the transaction, and it appears to me that, both as to existing facts and future facts, a condition would not be implied unless the new state of facts makes the contract something different in kind from the contract in the original state of facts. Thus in Krell v Henry[1903] 2 KB 740 , Vaughan Williams LJ finds that the subject of the contract was 'rooms to view the procession': the postponement, therefore, made the rooms not rooms to view the procession. This also is the test finally chosen by Lord Sumner in Bank Line Ltd v Authur Capel & Co[1919] AC 345 , agreeing with Lord Dunedin in Metropolitan Water Board v Dick Kerr & Co Ltd[1918] AC 119 at 128, where, dealing with the criterion for determining the effect of interruption in “frustrating” a contract, he says: “An interruption may be so long as to destroy the identity of the work or service, when resumed, with the work or service when interrupted.”
“As Mrs Graves and the children were technically trespassers Mr Graves is entitled at first sight to be paid an occupation rent by Mrs Graves for her enjoyment of the property but he is not entitled to be paid an occupation rent if his actions have been the cause of her remaining at the property.”
“However much the tone of some of Mrs Graves texts are to be regretted the point is that she was prepared to cut cackle and make an offer which was less than her claim was worth. Mrs Graves in those texts was offering to leave by the end of July 2005 if he repaid her£6,250 . She had paid£1,150 for the first month's rent and the£12,000 deposit. However as analysed above as the contract was void Mrs Graves was entitled to her entire£13,150 back less (on the basis she left by the31st July 2005 )£5,100 being 6 months occupation rent at£850 per month. She was therefore entitled to the return of£8,050 . She was prepared to get out for£6,250 . The reason why Mr Graves has lost further 15 months rent or so since the 31st July is because he did not accept an offer from Mrs Graves in figures that he ought to have accepted. I also do not consider an occupation rent right when the notices were not served until January 2006. I decline therefore to order occupation rentafter the31st July 2005 . Mrs Graves is entitled to the return of£13,150 less£5,100 occupation rent up to the31st July 2005 and is thus entitled to the payment of£8,050 .”