Born in Manchester, Behrens studied at Manchester Grammar School then at Rugby School. He was active in the family business and with the Manchester Chamber of Commerce. During World War I, he worked for the Serbian Relief Fund in Thessaloniki, and was awarded the Order of St Sava. Back in Britain, he became President of the Manchester Liberal Federation, and was an official of a large number of local bodies, including the Manchester Statistical Society, the Design and Industries Association, the Royal Manchester College of Music, the Hallé Concert Society and the University of Manchester. He also served as a JP.
Behrens was a keen supporter of the League of Nations Union, and later the United Nations Association, becoming vice-president of the World Federation of United Nations Associations. From 1955 to 1957, he served as President of the Liberal Party, and from 1959 to 1961 he was the party's Chair.
|Party political offices|
| President of the Liberal Party
| Chairman of the Liberal Party