The Feast of the Queenship of Mary was only established by Pius XII in 1954, and from what I've read, the pope did crown a statue of Mary in the Vatican the first time the feast was celebrated. So, your parish may have been imitating that practice.
Good info... it's nice to know the crowning
at the end of May was actually done by the Pope as that's where he fixed her feast day. Our bishop at the stadium and later parishes, probably did in fact follow his example.
However, as mentioned above, this only started in 1954. Before that, I don't believe there was any universal fixed time for the May crowning, other than sometime in the month of May.
The real question is, were there in fact May crownings before 1954? I know from reading there were May day celebrations but was there an actual crowning of Mary?
Now I really feel sad that certain trad chapels aren't following Pope Pius' example for the end of May.
I'd like to think he started a lovely tradition 70 years ago.
Sometimes it feels as if people just have to change things.