Aah, I see what they did there! I'm a bit slow on the uptake. It's taken me twenty odd years to "get" the reference: Bus Stop / Bun Stop - the former sandwich shop located next to the old Worswick Street Bus shelter, which has a sign with the typeface and colours of the old Northern Buses livery.
Now that was a great sandwich shop. It was a pity it closed. I used to love their cheese savoury baps and the all-day gut-buster breakfast sandwiches (not a menu item - just my name for them) I used to get from there. I can't remember when it closed, possibly 10-15 years ago, and I had almost forgotten about it until I spotted that some continuing renovations to the building had revealed the old shop sign.