The Anglo-Saxon invasions of the 5th and 6th centuries A.D. pushed the native Celts north and westward in Britain, to present-day Wales, and Northern England, taking the festival with them. Scotland, having a shared Gaelic culture and language with ancient Ireland, celebrated the festival of Samhain.

Meanwhile in England, the English Reformation in the 16th century de-emphasized Roman Catholic holy days like All Hallows Day and its associated eve.

With the rise of Guy Fawkes Night celebrations in 17th-century England, many Halloween traditions, especially the building of bonfires, were transferred to the new holiday, only six days from the old. On this patriotic holiday, children light bonfires and burn effigies of Guy Fawkes, a conspirator who tried to blow up the English Parliament building in 1605.

Today, adults in the UK often dress up and go to fancy dress parties or pubs and clubs on Halloween night.

The black cat was considered to be bad luck, whereas a white cat was considered to be good luck but in general the black cat is a lucky omen in the UK.

Souling died out in most areas of England by the mid-17th century, during the Protestant Reformation. There is no evidence that souling was ever practiced in North America, and trick-or-treating seems to have evolved there independently: the earliest report of ritual begging on Halloween is from 1915, and it did not become a widespread practice until the 1930s. Ritual begging on Halloween did not appear in the British Isles until the late 20th century, and imitates the American custom.

In Celtic parts of western Brittany, Samhain is still heralded by the baking of kornigouKornigou are cakes baked in the shape of antlers to commemorate the god of winter shedding his "cuckold" horns as he returns to his kingdom in the Otherworld.