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19 June 2017

Love thy neighbour, not their knotweed

If Network Rail hoped that defending proceedings brought by two homeowners in South Wales might set a helpful precedent in respect of claims relating to Japanese knotweed, it will have been disappointed. The claimant neighbours in Williams and another v NR Infrastructure Ltd (2 February 2017, Cardiff County Court) secured a judgment for the costs of treating the invasive weed plus damages for the diminution in the residual value of their bungalows (ie the reduced value even after the plant is treated, to reflect the stigma attaching to the properties), as well as general damages.

The plant here had been present on NR’s neighbouring embankment for at least 50 years. Japanese knotweed is a highly invasive weed, with shoots that can push through tarmac and damage building foundations. It is so potentially destructive that it is a criminal offence under the Wildlife and Countryside Act 1981 to plant or otherwise cause the weed to grow in the wild. Failing to control it can lead to a community protection notice being served under the Anti-social Behaviour, Crime and Policing Act 2014.

Although the claimant neighbours did not succeed on all points, the judgment may now encourage others to seek financial compensation from NR in respect of any encroachment of invasive plants onto their land.

Evidence of encroachment/damage

Although only one of the claimants produced evidence of the weed’s encroachment through photographs showing its underground stems (“rhizomes”) in a hole dug underneath the render of his bungalow, the court concluded on a balance of probabilities that rhizomes had encroached onto the other claimant’s land up to the foundations in the same way. There was no direct evidence that these rhizomes had penetrated the foundations or gone below them, but the expert evidence led the court to conclude that the roots were likely to have grown below the foundations of the claimants’ properties.

Despite this, the claims based on private nuisance failed because there was no evidence of actual damage to either bungalow or the foundations. (The reduced value of the bungalows is not a loss recoverable via a claim in private nuisance.)

Homes as investments

The claimants were, however, successful in persuading the court that the weed had unlawfully interfered with the “quiet enjoyment” or “amenity value” of their properties.

The judge agreed that the amenity value of a property could include the ability to dispose of it at a proper value. Following guidance in Bridlington Relay Ltd v Yorkshire Electricity Board [1965] 1 All ER 264, he agreed that the right to dispose of a residential property at a market value is “so important a part of an ordinary householder’s enjoyment of his property that such an interference should be regarded as a legal nuisance”.

The court accepted evidence that the “stigma” of the weed’s presence affects the ability to sell a property at its market value, even after treatment to remove it, including because of the difficulties of securing mortgage funding.

NR's knowledge

The claim required NR to have had knowledge or constructive knowledge of the state of affairs giving rise to the nuisance. Although there was actual knowledge once the claimants complained to NR in 2013, the court concluded that the company had constructive knowledge (ie ought to have known) of the plant at the rear of the claimants’ bungalows by 2008/2009. However, its constructive knowledge of the risk of damage and loss of amenity to adjoining properties as a result of the spread of Japanese knotweed was held to have arisen as late as 2012, when relevant guidance documents were published (a slightly surprising result, given that EG has been publishing articles about the problems for property owners caused by Japanese knotweed since as long ago as October 2005).

Adequacy of treatment

The court then considered whether NR had taken reasonable steps to treat the weed, as there had only been limited treatment after the complaints made in 2013.

Although the court acknowledged that NR had to prioritise the use of its resources, it felt that the treatment had been inadequate and that NR had failed reasonably to prevent interference with the claimants’ quiet enjoyment of their land since 2012. Indeed, NR’s approach to treating the weed was so poor that the claimants effectively abandoned their request for an injunction to require the company to treat the plant – although the mandatory injunction was declined by the judge in any event.

Attempted defences

Two strands of defence were attempted by NR based on the Supreme Court’s decision in Lawrence v Coventry (t/a RDC Promotions) and others [2014] UKSC 13; [2014] 1 EGLR 147. One of these was the contention that Japanese knotweed formed part of the established character of the locality. This argument was described by the judge as “wholly unsustainable” and he disagreed that this was a case where there should be “give and take” between adjoining owners.

It was also argued that NR could enjoy a prescriptive right to commit nuisance because of the presence of the plant on NR’s land for at least 50 years. This defence was raised late in the proceedings and the judge refused permission for it to be pursued. However, he indicated that it was unlikely to have succeeded in any case as it would have required proof of knowledge and acceptance by the claimants that the nuisance had continued for 20 years.

This article was written by Emma Humphreys, for more information please contact Emma on +44 (0)20 7203 5326 or

This article was published in Estates Gazette on 25th April 2017.