How did Ambridge get its name?

Answer 1

As in any fictional story, its authors wanted a purely-fictional but appropriate and believable name, in this case based somewhere in the English Midlands.

It means simply "at the bridge over the R. Am", and follows real examples like Cambridge.

Ahhh... Wait a moment...

I beg your pardon - I'd answered that after some questions about Alton Towers etc, so was a bit parochial, but scrolling down the page I see reference to a real "Ambridge" in Pennsylvania! I imagine its own derivation is as above!