Flying Spray @ Southampton uploaded.

Hi REG, you are right, it was the FLYING SPRAY. In those days (I was 16 years old) I noted several details. And it was definitely early June, 1965. I can post her seen from the back, but the quality of the photo is limited: http://www.shipspotting.com/gallery/photo.php?lid=3219765

The ship in the background is also a US-flag cargo vessel, operated by "American Export Isbrandtsen" Lines. I cannot tell which specific ship it is, but it is definitely one of the C1-B-class cargo ships formerly operated by Isbrandtsen Lines, similar to the famous "Flying Enterprise". In 1964 Isbrandtsen Lines merged with American Export Lines, after which the ships of both companies were repainted to look as shown in the photo above, so this photo was clearly taken during 1964, or sometime thereafter.

Thanks for the intersting background info, REG. I have added again the IMO number (found in Miramar).

This ship was named for Lieutenant-General Simon Bolivar Buckner Jr., the son of a man of the same name who had served as a Lieutenant-General in the Confederate Army during the Civil War. The commanding officer of ground forces during the Battle of Okinawa, Buckner was killed on Okinawa on 18 June 1945, becoming the most senior U.S. Army officer to be killed in action during World War II. The place where the U.S. forces landed in Okinawa subsequently became known as "Buckner Bay".