Nothing has since been said in your Lordships' House to cast any doubt upon this part of the decision. On the contrary, in Read v. J. Lyons & Co. Ltd. [1947] A.C. 156, 183, Lord Simonds made the same point in drawing attention to the distinction between negligence and nuisance. Negligence was based on fault but protected interests of many kinds. Liability in nuisance was strict but protected only interests in land:

 "For if a man commits a legal nuisance it is no answer to his injured neighbour that he took the utmost care not to commit it. There the liability is strict, and there he only has a lawful claim who has suffered an invasion of some proprietary or other interest in land."

      In Metropolitan Properties v. Jones [1939] 2 All E.R. 202 Goddard L.J., sitting at first instance, purported to follow Malone v. Laskey [1907] 2 K.B. 141. The defendant had been tenant of one of the plaintiffs' flats but had assigned his lease. The assignee disappeared and the tenant, who as original lessee remained liable for the rent, went back into possession. In response to an action for rent, he counterclaimed for nuisance constituted by the noise from a motor on the plaintiffs' premises which operated the central heating system. Goddard L.J. said that he would have awarded the defendant £21 damages but dismissed the counterclaim because he had no title. I think that this was wrong. The judge took Malone v. Laskey [1907] 2 K.B. 141 too far. The defendant was de facto in exclusive possession. That was enough to entitle him to sue. The fact that the missing assignee might have had a better claim to possession was no defence.

      But the concept of nuisance as a tort against land has recently been questioned by the decision of the Court of Appeal in Khorasandjian v. Bush [1993] Q.B. 727. The plaintiff was a young woman aged 18 living with her mother. The defendant was a former friend who pestered her with telephone calls. In the ordinary sense of the word, he was making a nuisance of himself. The problem was to find a cause of action which could justify the grant of an injunction to stop him. A majority of the Court of Appeal (Peter Gibson J. dissenting) held that she was entitled to sue in nuisance. Dillon L.J. brushed Malone v. Laskey [1907] 2 K.B. 141 aside. He said:

 "To my mind, it is ridiculous if in this present age the law is that the making of deliberately harassing and pestering telephone calls to a person is only actionable in the civil courts if the recipient of the calls happens to have the freehold or a leasehold proprietary interest in the premises in which he or she has received the calls."

      This reasoning, which is echoed in some academic writing and the Canadian case of Motherwell v. Motherwell (1976) 73 D.L.R. (3rd) 62 which the Court of Appeal followed, is based upon a fundamental mistake about the remedy which the tort of nuisance provides. It arises, I think, out of a misapplication of an important distinction drawn by Lord Westbury L.C. in St. Helen's Smelting Co. v. Tipping 11 H.L.C. 642, 650. In that case, the plaintiff bought a 1300 acre estate in Lancashire. He complained that his hedges, trees and shrubs were being damaged by pollution from the defendants' copper smelting works a mile and a half away. The defendants said that the area was full of factories and chemical works and that if the plaintiff was entitled to complain, industry would be brought to a halt. Lord Westbury said:

 "My Lords, in matters of this description it appears to me that it is a very desirable thing to mark the difference between an action brought for a nuisance upon the ground that the alleged nuisance produces material injury to the property, and an action brought for a nuisance on the ground that the thing alleged to be a nuisance is productive of sensible personal discomfort. With regard to the latter, namely the personal inconvenience and interference with one's enjoyment, one's quiet, one's personal freedom, anything that discomposes or injuriously affects the senses or the nerves, whether that may or may not be denominated a nuisance, must undoubtedly depend greatly on the circumstances of the place where the thing complained of actually occurs. If a man lives in a town, it is necessary that he should subject himself to the consequences of those operations of trade which may be carried on in his immediate locality, which are actually necessary for trade and commerce, and also for the enjoyment of property, and for the benefit of the inhabitants of the town and of the public at large. If a man lives in a street where there are numerous shops, and a shop is opened next door to him, which is carried on in a fair and reasonable way, he has no ground for complaint, because to himself individually there may arise much discomfort from the trade carried on in that shop. But when an occupation is carried on by one person in the neighbourhood of another, and the result of that trade, or occupation, or business, is a material injury to property, then there unquestionably arises a very different consideration. I think, my Lords, that in a case of that description, the submission which is required from persons living in society to that amount of discomfort which may be necessary for the legitimate and free exercise of the trade of their neighbours, would not apply in circumstances the immediate result of which is sensible injury to the value of the property."

      St. Helen's Smelting Co. v. Tipping was a landmark case. It drew the line beyond which rural and landed England did not have to accept external costs imposed upon it by industrial pollution. But there has been, I think, some inclination to treat it as having divided nuisance into two torts, one of causing "material injury to the property," such as flooding or depositing poisonous substances on crops, and the other of causing "sensible personal discomfort" such as excessive noise or smells. In cases in the first category, there has never been any doubt that the remedy, whether by way of injunction or damages, is for causing damage to the land. It is plain that in such a case only a person with an interest in the land can sue. But there has been a tendency to regard cases in the second category as actions in respect of the discomfort or even personal injury which the plaintiff has suffered or is likely to suffer. On this view, the plaintiff's interest in the land becomes no more than a qualifying condition or springboard which entitles him to sue for injury to himself.

      If this were the case, the need for the plaintiff to have an interest in land would indeed be hard to justify. The passage I have quoted from Dillon L.J. is an eloquent statement of the reasons. But the premise is quite mistaken. In the case of nuisances "productive of sensible personal discomfort," the action is not for causing discomfort to the person but, as in the case of the first category, for causing injury to the land. True it is that the land has not suffered "sensible" injury, but its utility has been diminished by the existence of the nuisance. It is for an unlawful threat to the utility of his land that the possessor or occupier is entitled to an injunction and it is for the diminution in such utility that he is entitled to compensation.

      I cannot therefore agree with Stephenson L.J. in Bone v. Seale [1976] 1 W.L.R. 797 when he said that damages in an action for nuisance caused by smells from a pigsty should be fixed by analogy with damages for loss of amenity in an action for personal injury. In that case it was said that "efforts to prove diminution in the value of the property as a result of this persistent smell over the years failed." I take this to mean that it had not been shown that the property would sell for less. But diminution in capital value is not the only measure of loss. It seems to me that the value of the right to occupy a house which smells of pigs must be less than the value of the occupation of an equivalent house which does not. In the case of a transitory nuisance, the capital value of the property will seldom be reduced. But the owner or occupier is entitled to compensation for the diminution in the amenity value of the property during the period for which the nuisance persisted. To some extent this involves placing a value upon intangibles. But estates agents do this all the time. The law of damages is sufficiently flexible to be able to do justice in such a case: compare Ruxley Electronics and Construction Ltd. v. Forsyth [1996] A.C. 344.

      There may of course be cases in which, in addition to damages for injury to his land, the owner or occupier is able to recover damages for consequential loss. He will, for example, be entitled to loss of profits which are the result of inability to use the land for the purposes of his business. Or if the land is flooded, he may also be able to recover damages for chattels or livestock lost as a result. But inconvenience, annoyance or even illness suffered by persons on land as a result of smells or dust are not damage consequential upon the injury to the land. It is rather the other way about: the injury to the amenity of the land consists in the fact that the persons upon it are liable to suffer inconvenience, annoyance or illness.

      It follows that damages for nuisance recoverable by the possessor or occupier may be affected by the size, commodiousness and value of his property but cannot be increased merely because more people are in occupation and therefore suffer greater collective discomfort. If more than one person has an interest in the property, the damages will have to be divided among them. If there are joint owners, they will be jointly entitled to the damages. If there is a reversioner and the nuisance has caused damage of a permanent character which affects the reversion, he will be entitled to damages according to his interest. But the damages cannot be increased by the fact that the interests in the land are divided; still less according to the number of persons residing on the premises. As Cotton L.J. said in Rust v. Victoria Graving Dock Co. (1887) 36 Ch. D.113, 130:

 ". . . where there are divided interests in land the amount of damages to be paid by the defendants must not be increased in consequence of that subdivision of interests."

      Once it is understood that nuisances "productive of sensible personal discomfort" do not constitute a separate tort of causing discomfort to people but are merely part of a single tort of causing injury to land, the rule that the plaintiff must have an interest in the land falls into place as logical and, indeed, inevitable.

      Is there any reason of policy why the rule should be abandoned? Once nuisance has escaped the bounds of being a tort against land, there seems no logic in compromise limitations, such as that proposed by the Court of Appeal in this case, requiring the plaintiff to have been residing on land as his or her home. This was recognised by the Court of Appeal in Khorasandjian v. Bush [1993] Q.B. 727 where the injunction applied whether the plaintiff was at home or not. There is a good deal in this case and other writings about the need for the law to adapt to modern social conditions. But the development of the common law should be rational and coherent. It should not distort its principles and create anomalies merely as an expedient to fill a gap.

      The perceived gap in Khorasandjian v. Bush [1993] Q.B. 727 was the absence of a tort of intentional harassment causing distress without actual bodily or psychiatric illness. This limitation is thought to arise out of cases like Wilkinson v. Downton [1897] 2 Q.B. 57 and Janvier v. Sweeney [1919] 2 K.B. 316. The law of harassment has now been put on a statutory basis (see the Protection from Harassment Act 1997) and it is unnecessary to consider how the common law might have developed. But as at present advised, I see no reason why a tort of intention should be subject to the rule which excludes compensation for mere distress, inconvenience or discomfort in actions based on negligence: see Hicks v. Chief Constable of the South Yorkshire Police [1992] 2 All E.R. 65. The policy considerations are quite different. I do not therefore say that Khorasandjian v. Bush [1993] Q.B. 727 was wrongly decided. But it must be seen as a case on intentional harassment, not nuisance.