They did have it all the way through the 80s and 90s as the largest airline operator at Manchester flying to Southampton, Belfast City, Knock and the Channel Islands and the likes of Southampton to Brussels.
Is it not part of the brand and identity? I don’t recall anyone suggesting Aer Lingus drop the shamrock when they were flying Gatwick to Bucharest or that LOT should drop its suffix given its expansion at Budapest. Don’t see the issue myself.