John F Kennedy at Millbay Docks?

On the Plymouth council website, it says that John F Kennedy once disembarked at Millbay Docks in Plymouth. I've never seen this mentioned anywhere else and I'm sure that if a historical figure as important as John F Kennedy had visited Plymouth, it would be mentioned elsewhere. Also, I have never seen any photos of JFK at Plymouth. The site doesn't say when the incident was meant to have happened and I wonder if it's an error? Does anyone know of any information regarding his visit to Plymouth?
Kennedy made his first trip to England in September 1935 when he travelled with his parents and his sister, Kathleen. He also sailed to France in July 1937 and in June 1938, he travelled to London with his father and his brother, Joe. His father was Roosevelt's U.S. Ambassador to the Court of St. James, at the American embassy in London. In August of the same year, the family stayed in a villa near Cannes. Later, in 1939, Kennedy toured Europe, the Soviet Union, the Balkans, and the Middle East before travelling to Czechoslovakia and Germany before returning to London on the 1st September , 1939 which was the day Germany invaded Poland. On 3rd September of the same year, the family attended speeches at the House of Commons which endorsed the United Kingdom's declaration of war on Germany. Kennedy was sent as his father's representative to help with arrangements for American survivors of the SS Athenia, before flying back to the U.S. from Foynes, Ireland to Port Washington, New York on his first transatlantic flight.
I intend to investigate his trip to Plymouth further so check for later blog posts to see what I discover. Perhaps, while on one of the trips mentioned, he landed at Millbay. The council's web page can be found here:
http://www.plymouth.gov.uk/millbay_docks_25-32.pdf
Other celebrities mentioned on the site that diembarked at Milbay include General Allenby, Charlie Chaplin, Maurice Chevalier, Winston Churchill,
Clemenceau, Bebe Daniels, Marlene Dietrich,Walt Disney, Douglas Fairbanks, Helen Keller, Pierre Laval,Vivian Leigh, Lloyd George, Ben Lyon, Anna Pavlova, General Pershing, Mary Pickford, Cecil Rhodes, Bernard Shaw, General Smuts and  HG Wells.
I hope to write about some of these visitors in later posts.