The grey squirrel was introduced into the UK in the 1870s from North America as an ornamental species to populate the grounds of stately homes. Introductions occurred until 1930. At this time the damage caused by the grey squirrel was recognised and it was made illegal to release a grey squirrel into the wild. Grey squirrels have rapidly spread and colonised much of mainland England with detriment to our wildlife, especially the native red squirrel, and tree species.
However, watching Grey squirrels is a pastime for many and despite their negative effect on native wildlife.
Continued Reflections from my World. 
what negative effects do they do?
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https://www.woodlands.co.uk/blog/flora-and-fauna/damage-by-grey-squirrels/
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that’s interesting Andy, I guess our squirrels are more well mannered?
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It seems every country has been invaded by animals and birds from other countries. I know squirrels in general can cause a lot of problems.
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I enjoy watching squirrels but feel sad for our native red squirrels which are so rare now.
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Wow. I never knew any of this. They are ingenious creatures. I live with them. Whose brilliant idea was it to import them? It reminds of relocating beavers to Argentina. Although beavers are more effective changers of geologic architecture than grey squirrels.
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In the UK a lot of non native animals were imported to furnish rich landowners estates without an understanding of the effects on native wildlife. We have programmes to reintroduce some animals such as beavers and sea eagles which were native but had become extinct here.
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We only had black squirrels in Canada and when we moved to the States in 1966, we only had Fox squirrels – now neighborhoods and parks are full of Fox, gray and black squirrels.
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