Her official birthday is June. Next year, I believe, we are getting an extra public holiday for her jubilee (first Monday in June?) and the late Bank Holiday in May is being moved from the last Monday in May to the first Tuesday in June so that we all have a lovely four day weekend.
Of course, I could have just been dreaming that scenario (like the dream I had on Saturday when I kept dreaming that I saw a black camel standing on a roundabout with very elaborate headress)!