An historic one from my own locality. Buckle of Duns, which finished in 1986 when the owner (the late Malcolm Buckle) retired, was well-known both in the Borders and beyond for its high standards of maintenance and turnout. It always bought new and when its vehicles did come up for sale, buyers knew they were getting ones that had been well cared for. Its vehicles were known as the "pigeon buses" locally because the fleet colours were blue and grey; as a child, whenever these were mentioned - and as several of my neighbours raced pigeons - I had visions of passengers sitting in the backs of the lorries used to transport the pigeons to races!
I remember talking with Malcolm a few years after he retired and he told me that the reason why the company closed on his retirement was down to two things. One, he always said that he would run the buses until he turned 65, which he did. The other was because deregulation was imminent; in the Borders, buses were deregulated on 18th August 1986 (at the start of the Scottish school year), rather than in the October, and Malcolm didn't want to pass the company on within the family in case Lowland Scottish ran it off the road. Far better for all to go out on a high.