Some neighbors have good points and bad points...

Grey squirrels were first introduced, several times but unsuccessfully, in the early 19th century. Later 19th-century introductions were also multiple, but successful. What had changed?

Mainly, the Enclosure Acts had put much land under people who then managed it for field sports, persecuting squirrel predators such as pine martens and goshawks. So grey squirrels had a lucky break and began to replace native red squirrels, since they carry a disease fatal to reds, which they themselves are immune to.

Whilst we have had fun pointing out in our squirrel envy video how squirrels help woodlands by inadvertently planting trees because they forget where they buried their nuts, in fact, it was much better for UK woodlands when red squirrels performed this service. Sadly, greys are not an all-around good neighbor to trees as they eat the bark of young trees, especially oaks, often killing them as a result.