When Guide Friday (as was) were expanding their open-top city tours to a number of places (1988?), they went and talked to Edinburgh's Lothian Regional Transport about a partnership arrangement. Guide Friday felt that LRT weren't running their city tours very well. No guide, ordinary (roofed) double-deck buses etc etc. LRT said that there was no market for open-top tours in Edinburgh - "its too cold".
So Guide Friday went to the other local bus operator - in those days Eastern Scottish (now, alas, part of First). They parked their open-toppers in the Eastern Scottish depot and got Eastern Scottish to look after them. When
GF▸ started operating the open-toppers they were an instant success. So much so that, within a week, LRT had started to take the roofs off their tour buses.
Eventually LRT tried to retaliate by running rival open-top tours on GF's home turf in Stratford-upon-Avon.
Meanwhile, you might like a Swiss example,
]https://www.thelocal.ch/20170713/postbus-launches-new-open-top-coach[url][/url].