An English policeman wearing a gorilla costume while crawling the London Marathon has finally finished the race, almost a week after starting.

Metropolitan Police officer Tom Harrison, who goes by the name "Mr. Gorilla," raised a reported 26,000 pounds ($45,991.90 Cdn) for the Gorilla Organization, which is dedicated to conserving gorillas in countries including Rwanda and Uganda.

Britain Gorilla Marathon

Tom Harrison also known as Mr. Gorilla makes his way crawling along part of the London Marathon course in aid of the charity 'Gorilla Organization' on Thursday. (Alastair Grant/The Associated Press)

The 41-year-old Londoner started the 42.2-kilometre route last Sunday and crossed the finish line on Saturday.

Harrison slept at friends' houses in the evenings after completing around 10 to 12 hours and 4.5 miles per day. He has swapped between crawling on his hands and knees and up on his hands and feet to save his blistered knees.

He crossed the finish line in central London flanked by his two sons — and beating his chest.