Aged eleven Kenworthy was invited to attend the Royal College of Art by John Skeaping, then Professor of the Department of Sculpture. Later Skeaping wrote of him: "He is, to my mind, the best sculptor of animals to make an appearance this century". Since then he has been widely acknowledged as the leading sculptor in his field.

He studied at the College from 1954-59 and then at the Royal Academy Schools from 1961-64. He won ten scholarships, including the Royal Academy Gold Medal in 1964. During this time he also studied animal anatomy at the Royal Veterinary College, before going on to dissect wild animals in the Anatomy Department of University College in Nairobi under the guidance of Prof.R.R. Hoffman.

 
                   
               
 
In 1993 he was commissioned by the Duke of Westminster to create a sculpture to be placed on a lake in the gardens at Eaton Hall, in Cheshire. A second casting of the piece, depicting a lioness chasing a lesser kudu, was placed in Upper Grovesnor Gardens, in Central London. The thirty foot bronze was dedicated by the Duke to mark the opening of the gardens for the people of Westminster in June 2000.