When my son was four in England -- Actually, he was four everywhere, to be honest.  If we're being strict about it, wherever he went, he was four that year.
私の息子がイギリスで４歳だった頃 正直言うと、あの頃息子はどこにいたって４歳だったんですが そう！あの年息子はどこに行っても４歳でした