The group action involves 152 households who allege that the odour from the Westmill II Landfill site in Ware, Hertfordshire, has seriously affected their quality of life. In many cases residents stated they were prevent from being able to open their windows or use their gardens as they wish due to the odour nuisance from the Westmill Landfill site. The claims range over five years from when the site first accepted waste in July 2004 until October 2009. Biffa sought to argue, amongst other things, that the operation of the site pursuant to the terms of a permit gave rise to a defence of statutory authority. At first instance, the Judge held that the correct test was whether Biffa was a “reasonable user” and the nuisance claim failed on that basis because Biffa had complied with its permit and had not acted negligently. He also noted that, in any event, a threshold of at least one complaint per week concerning the odorous smells had not been satisfied. The Claimants appealed. Court of Appeal held that compliance with environmental permit is no defence to nuisance claim. Nuisance is traditionally defined as an unreasonable interference with a neighbours comfortable and convenient enjoyment of their land. There must, therefore, be a real interference, taking location into consideration. As well as ruling that there was no requirement to set a threshold of the number of complaints that a resident would have to make before a nuisance was recognised as actionable, the Court of Appeal also confirmed that in deciding whether a use of land was “reasonable”, regard had to be had, only to the question of what “an ordinary person could reasonably be expected to put up with.”This was the longstanding common law test. An examination of the terms on which a defendant is using its land (i.e. via an environmental permit) was not necessary. The Court of Appeal also dismissed Biffas cross appeal that it had statutory authority to commit a nuisance courtesy of its operating permit from the Environment Agency, and was thus immune from common law private nuisance claims.