I can remember early test flying of Concorde which including supersonic runs down the west coast and it definitely flew supersonic over the west of Scotland as I can vividly remember the sound even today. So those Lightning flights were not the last official supersonic flights over land.
Heard many Concorde booms later along the South Coast when, if weather conditions were right, booms from Air France flights over the Channel would hit the coast. Used to rattle the windows quite a bit!