Interestingly, the UK now holds 10% of the world population of Chinese Water deer, a species introduced shortly after WW2 but not doing very well in its native homeland. Concurrently, grey squirrels now grossly outnumber the native reds, spreading diseases such as Squirrelpox. Globally, areas such as the Galapagos and Australia have also suffered similar scenarios. So, when do we say enough? Is it right that invasive species remain (let's not forget that rabbits were introduced by the Normans) or do we cull such invaders and invest in repopulating native species?