In a previous edition of the Bulletin (August 2017), we discussed the County Court case of Williams & Waistell v Network Rail Infrastructure Ltd in which two adjoining property owners succeeded in a private nuisance claim against Network Rail who had failed to take appropriate steps to prevent the spread of Japanese knotweed roots and shoots from its land onto the Claimants’ land.

The Court of Appeal has recently handed down judgment on Network Rail’s appeal and it has upheld the decision at first instance, albeit for different reasons to those given by the Recorder (Network Rail Infrastructure Limited v Williams & Waistell [2018] Civ 1514).


Japanese knotweed, described by the Environment Agency as “indisputably the UK’s most aggressive, destructive and invasive plant”, has long been a scourge on landowners. The plant is extremely fast growing and according to the RICS paper on “Japanese Knotweed and Residential Property”, once established, its “eradication requires steely determination”. Japanese knotweed poses a particularly significant risk to properties within seven metres of the plant and it can affect drains, paving, walls and outbuildings and conservatories. For this reason, the presence of knotweed can affect the valuation of a property and it is likely to influence a lender’s decision when offering a mortgage on the affected property.

First instance decision

Network Rail owned the land directly behind the Claimants’ properties, comprising an access path leading to an embankment which dropped down to the train line. Japanese knotweed had been present on the embankment for at least 50 years. The Claimants issued private nuisance claims against Network Rail on the basis that:

  1. Network Rail was liable for the encroachment of the Japanese knotweed onto the Claimants’ land even though the Claimants were unable to prove that it had actually caused any physical damage to their land (the “Encroachment Claim”); and
  2. The presence of Japanese knotweed on Network Rail’s land in close proximity to the boundary of the Claimants’ properties constituted a significant interference with the Claimants’ quiet enjoyment or amenity value of their properties as it affected their ability to sell their properties at the true market value (the “Quiet Enjoyment/Loss of Amenity Claim”).

The Claimants sought damages and an injunction requiring Network Rail to treat and eliminate the knotweed. At first instance, the County Court Recorder rejected the Encroachment Claim because no physical damage had been caused by the encroachment. However, the Recorder held that the Quiet Enjoyment/Loss of Amenity Claim should succeed because the amenity value of a property can, in principle, include the ability to dispose of the property at a proper value.

The Recorder found that Network Rail was aware of the presence of the plant and had constructive knowledge of the risk posed by the plant and its potential damage. Network Rail had failed to carry out its obligation as a reasonable landowner to eliminate and prevent interference with the Claimants’ quiet enjoyment of their properties and this breach of duty had caused both a continuing nuisance and damage. Accordingly, the Claimants were awarded damages.

Court of Appeal decision

Network Rail appealed the first instance decision and the Court of Appeal held that:

  1. The Recorder was wrong, in principle, to conclude that the presence of Japanese knotweed on Network Rail’s land within close proximity to the Claimants’ properties was an actionable nuisance simply because it diminished the market value of the Claimants’ properties. “The purpose of the tort of nuisance is not to protect the value of property as an investment or a financial asset”... There must be physical damage to the property”.
  2. However, the Court of Appeal did not agree with the Recorder’s decision to reject the claim based on the spread of the knotweed’s rhizomes to the Claimants’ land. The Court noted that Japanese knotweed and its rhizomes can be described as a “natural hazard” and their mere presence “imposes an immediate burden on the owner of the land in terms of an increased difficulty in the ability to develop, and in the cost of developing, the land, should the owner wish to do so”. As such, “they are a classic example of an interference with the amenity value of the land”.

As Network Rail had actual knowledge of the presence of knotweed since 2013, it was, or ought to have been, aware of the risks it posed to adjoining properties, and it failed reasonably to prevent the interference with the Claimants’ enjoyment of their properties, an actionable nuisance had arisen. If the Claimants were required to prove damage in order to complete the cause of action, this was constituted by the diminished ability of the Claimants to use and enjoy the amenity of their properties.


This judgment is significant because it reaffirms the decision that the presence of Japanese knotweed can be an actionable nuisance before it has caused physical damage to neighbouring land because of its effect on the amenity value and quiet enjoyment of such land.

Property owners, managers and insurers should be aware of the potential liability they are exposed to by the presence of Japanese knotweed. Careful management, weed control and eradication programmes will be prudent. When acquiring property, purchasers should be mindful of the presence of the plant and raise any queries with their surveyors and solicitors.