is this a crime show?

It's supposed to be! It's certainly not in the same class as Agatha Christie, 'Midsomer Murders' or even 'New Tricks'. I find it rather disappointing as a murder mystery show!

Extremely "light entertainment" would be a more accurate description. The series does not have the grittiness of most U.K. crime dramas. More like "Midsomer Murders" than anything else. The scripts are using main characters of the original G.K. Chesterton novels, however the scripts are not based on his novels nor are they up to that standard imho.

Locked my wire coat-hanger in the car - good thing that I always carry spare keys in my pocket :)

It pretends to be.

This is by far the worst crime show ever made by the BBC. Bad acting, badly directed, inaccurate, boring, badly written, an ensemble of actors out of retirement... Huge disappointment!