I can't see why the road isn't two-way, or one-way with a bus lane. Does
anyone know why it is the way it is? I can't think of any similar road
anywhere.

I recall (20+ years ago) this road was two lanes but still part of the
one-way system. It was made single lane after several cars ended up in the
front rooms of the houses at the 90 degree bend (outside the town park
entrance). The brickwork flowerbed was constructed and the left lane fitted
with bollards to make it cycle only. I guess now they'd just put a camera up
to slow people down. Then it was all done with design

Regards,
Dave