Londons trafalgar square Christmas tree is traditionally given by which country?

The Trafalgar Square Christmas tree is a decorated Christmas tree that is given to the people of London by the City of Oslo as a token of gratitude for British support during World War II. The tree is usually a Norway spruce, and is erected in Trafalgar Square in early December. The tree is decorated with lights and ornaments, and is a popular tourist attraction. The tradition of the Trafalgar Square Christmas tree began in 1947, and has continued every year since then.