Sciurus carolinensis; the Grey Squirrel
This species originates from North America and was brought to UK for a series of introductions, for some reason, between 1876 and 1929. It has become widespread and as it moved across the country it began to outcompete the smaller red squirrel (Sciurus vulgaris) whilst also spreading a disease called squirrel pox to which it is almost entirely immune whilst the red has no defense; death was almost guaranteed once the disease was caught. There are an estimated 2,600,000 in the UK with 2 million of these in England. They are thought to be increasing and this appears to be the case in Cheshire.