So, some photos attached make this obvious - it's based on the WrightBus New Bus for London.
It's currently on the Lego Idea's site at https://ideas.lego.com/projects/154570/ - I'd be grateful of support to get this to the next stages. Comments and thoughts always appreciated, too :)
Key features:
Opening front and centre doors
An open rear platform for minifigs to jump on and off
A removable roof to access the top deck to place minifigs inside
A removable portion top deck to allow access to the bottom deck
Blank destination panels for customisation within the end pack
Two staircases for top deck access
"Push Bell" and grab poles on the lower deck for minifigs to stop the bus
https://flic.kr/s/aHskEj6J68 has some images:
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