I cannot vouch for the absolute validity or authority, but I found the following at http://www.mninter.net/~blkeagle/hats.htm.
"The red beret was introduced originally as part of the Leadership Corps uniform in 1971. The Leadership Corps, as rolled out then, were the forerunner to today's Venture Crew -- three or more boys aged 14 or over, whose jobs it was to work with and advise the Troop's elected leadership, while training and coaching younger Scouts and continuing on their advancement. Leadership Corps members wore the kelly green Scout shirts with special "SCOUT BSA" strips (that's