Question: The cast of Bulldog Drummond Comes Back included an English actor who as also an amateur champion of what sport?

Context paragraphs:
Reginald Denny (actor): Reginald Denny (born Reginald Leigh Dugmore, 20 November 1891 – 16 June 1967) was an English stage, film and television actor as well as an aviator and UAV pioneer.  He was once an amateur boxing champion of Great Britain.

Bulldog Drummond at Bay (1947 film): Bulldog Drummond at Bay is a 1947 American thriller film directed by Sidney Salkow and starring Ron Randell for the first time as the British sleuth and adventurer Bulldog Drummond.  The cast also includes Anita Louise, Patrick O'Moore and Terry Kilburn.

Bullshot (film): Bullshot is a 1983 film, based on the stage play "Bullshot Crummond".  The name comes from a parody of the 1929 film, on which it is loosely based, "Bulldog Drummond".

Knock-Out (novel): Knock-Out was the eighth Bulldog Drummond novel.  It was published in 1932 and written by H. C. McNeile under the pen name Sapper.  It was adapted into the film "Bulldog Drummond Strikes Back".

Bulldog Drummond Comes Back: Bulldog Drummond Comes Back is a 1937 American film starring John Howard.  Top-billed John Barrymore plays his friend Colonel Nielsen.  The picture was directed by Louis King and the supporting cast includes series regular Louise Campbell, Reginald Denny, E.E. Clive, and J. Carrol Naish.

Margaret Leighton: Margaret Leighton, CBE (26 February 1922 – 13 January 1976) was an English actress, known for her exquisite sense of grandeur and refinement.  Her film appearances included "Under Capricorn" (1949), "Calling Bulldog Drummond" (1951), "Carrington V.C." (1955) and "The Best Man" (1964).  For "The Go-Between" (1971), she won the BAFTA Award for Best Actress in a Supporting Role and was nominated for the Academy Award for Best Supporting Actress.

Bulldog Drummond Strikes Back (1947 film): Bulldog Drummond Strikes Back is a 1947 film American thriller film directed by Frank McDonald and starring Ron Randell, Gloria Henry and Patrick O'Moore.  The film is loosely based on the H. C. McNeile novel "Knock-Out.

Ronald Colman: Ronald Charles Colman (9 February 1891 – 19 May 1958) was an English actor, popular during the 1930s and 1940s.  He won an Academy Award for Best Actor for "A Double Life" (1947) and received nominations for "Random Harvest" (1942), "Bulldog Drummond" (1929) and "Condemned" (1929).  Colman starred in several classic films, including "A Tale of Two Cities" (1935), "Lost Horizon" (1937) and "The Prisoner of Zenda" (1937).  He also played the starring role in the Technicolor classic "Kismet" (1944), with Marlene Dietrich, which was nominated for four Academy Awards.

Bulldog Drummond Strikes Back (1934 film): Bulldog Drummond Strikes Back is a 1934 American comedy-mystery-adventure film directed by Roy Del Ruth.  The film stars Ronald Colman and Loretta Young.  It was a loose sequel to the 1929 film "Bulldog Drummond" which had also starred Colman.

Calling Bulldog Drummond: Calling Bulldog Drummond is a 1951 British crime film directed by Victor Saville and featuring Walter Pidgeon, Margaret Leighton, Robert Beatty, David Tomlinson, and Bernard Lee.  It featured the character Bulldog Drummond created by the novelist Herman Cyril McNeile, which had seen a number of screen adaptations.  A novel tie-in was also released in 1951.  It was made by the British subsidiary of MGM at Elstree Studios.  The film's sets were designed by the art director Alfred Junge.

Supporting paragraphs: Bulldog Drummond Comes Back Reginald Denny (actor)
Answer: boxing