"Richard J." gurgled happily, sounding much
like they were saying:

The practice of putting up a few little non-standard signs warning of
trees whose upper trunks or major branches encroach over the kerb line
on bus routes has always seemed to me to be inadequate and too casual.
If it's a branch, then cut it off. If the trunk itself is a danger,
then either narrow the carriageway or remove the tree. If the
tree-huggers don't like that, they can plant another tree, further from
the kerb. Street trees look nice and generally should be preserved, but
not at the cost of bus passegers' and pedestrians' lives.

I wonder how many double-decker buses have passed that tree without
hitting it?

Since I suspect it is rather considerable, I think we can discount the
positioning of the tree itself - unless it moved recently.