A "leap hour" would presumably require changing the UTC-equivalent itself.
Earlier I proposed exactly the opposite. Never change UTC, just redefine your timezone to create an apparent leap hour. Since we already do this twice a year in many countries, it should be less of a problem.
Interesting idea! So basically every several hundred years we would shift the center of time farther and farther away from Greenwich. That explains why the British are opposed. I was thinking timezones would stay relative to Greenwich and the "leap hour" would be thousands of accumulated leap seconds applied at once. Your proposal sounds better.
Earlier I proposed exactly the opposite. Never change UTC, just redefine your timezone to create an apparent leap hour. Since we already do this twice a year in many countries, it should be less of a problem.