The award is in recognition of his significant contribution to charitable work for the Bletchley Park Trust.
Mr Greenish (pictured) was director of the Bletchley Park Trust from April 2006 until January 2012.
His successor as chief executive Iain Standen said: “Simon’s contribution to saving Bletchley Park for the nation was enormous.
"When he took over as CEO six years ago it was struggling to stay open on a month-to-month basis. In contrast, I took over a vibrant going concern and I had the exciting task of writing a ten-year vision.”