Some of Norway's top musicians have taken part in a special concert for the lighting of Trafalgar Square's Christmas tree.
The tree is a gift from Norway
Singer Sissel and the Oslo Cathedral Boys' Choir performed traditional Norwegian folk music and pop music.
The tree is a gift to Londoners from the people of Norway, a tradition which has been upheld since 1947.
Mayor Ken Livingstone said the tree was "a great symbol of friendship between London and Norway".
The mayor of Oslo, Per Ditlev-Simonsen, was also expected at the ceremony on Tuesday.
Mr Livingstone said: "The Trafalgar Square Christmas tree is a central part of Christmas in London."