Of the 1,892 non-native plants listed in the 2005 audit of non-native species in England, only 66 were described as having a negative environmental impact (Hill et al. 2005). A similarly small proportion was identified in the 2001 Scottish audit (Welch et al. 2001). Hence, it would be hard to disagree with Pearman & Walker's conclusion that 'the vast majority of naturalised alien plants [in Britain] are benign' (Pearman & Walker 2009).