What sporting event took place at Aintree five times between 1955 and 1962?

Aintree Racecourse is a racecourse in Aintree, Metropolitan Borough of Sefton, Merseyside, England. The racecourse is best known for annually holding the world-famous Grand National steeplechase. Steeplechasing at Aintree was introduced in 1836, though flat racing had taken place there for many years prior to this. It is regarded as the most difficult of all courses to complete successfully, with 16 steeplechase fences including renowned obstacles the Chair, Foinavon, Valentine's, Canal Turn and Becher's Brook.

Aintree has also been used as a venue for motor racing. The British Grand Prix was staged there on five occasions, in 1955, 1957, 1959, 1961 and 1962. In addition to the Grand Prix, the circuit also held 11 non-championship Formula 1 races, known as the Aintree 200, first won by Stirling Moss in 1954 with the last winner being Jack Brabham, in April 1964.