The red squirrel is a protected species in the UK and is included in the Wildlife & Countryside Act 1981 (WCA) (amended by the Countryside & Rights of Way Act 2000). As a result it is an offence to intentionally kill or injure a red squirrel, to intentionally or recklessly damage or destroy any structure or place a red squirrel uses for shelter or protection, or disturb a red squirrel while it occupies such a place.
The grey squirrel is legally regarded as an invasive non-native species and has no protection under the WCA. They are listed in the IUCN international list of 100 worst invasive non-native species, which highlights the damage that grey squirrels cause to our native flora and fauna; a problem severe enough to be recognised at a level of global significance. This legal standing and recognition as a detrimental invasive species means that it is also illegal to release a grey squirrel into the wild, or allow one to escape.