The British actress portrayed The Queen in the 2006 biopic, and described her "idiocy" upon missing the Silver Jubilee in 1976, but is looking forward to this year's Diamond festivities.
"I didn't celebrate and was appalled by the celebrations. In my idiocy, I missed out," she told Woman & Home.
"Actually a lot of the street parties people held looked great fun, so silly me."
She added: "I feel kind of proud about this jubilee. The reign of the Queen has provided amazing continuity in a time when that is so rare."
Helen Mirren will take part in the Windsor Castle Diamond Jubilee pageant to celebrate The Queen's love of horses later this month.
Robbie Williams, Kylie Minogue and Stevie Wonder will be among the stars performing at the upcoming Diamond Jubilee concert on June 4.