It is in BrE.I have never heard that expression (collar felt)
Police can make a collar (arrest)
You can be collared (arrested)
But to have your collar (piece of material around the neck) felt could happen when you get your hair cut or when someone hugs you, not when you are arrested.
It is not an idiom.
If you have a question about the English language and would like to ask one of our many English teachers and language experts, please click the button below to let us know: