Complex sentence: From 1961 to 1965, a series of non-championship Formula 1 races were also held on the same weekends, welcoming drivers such as John Surtees, Jim Clark, Dan Gurney and Jack Brabham.
Split into simpler sentences: From 1961 to 1965, a series of non-championship Formula 1 races were held also at the same weekend. Pilots were, among others, John Surtees, Jim Clark, Dan Gurney, Jack Brabham.