Irish fingering

A contributor to a discussion about domestic politics on RTE Radio 1 on Friday morning talked of putting a tricky issue on to the long finger. From the context I understood this to mean what we might call kicking into the long grass (in the hope that it might go away).

But surely something would stay all too plainly in view if it were on the prominent middle finger? Could the phrase perhaps imply something worse – referring to a gesture which is at least rude, if not insultingly obscene?

The OED offered no help as to a figurative or colloquial meaning, defining long finger as merely the middle, or sometimes the three middle, fingers.

The Macmillan Dictionary blog suggests that to put something on an mhéar fhada in Irish means to postpone something. The Phrase Finder suggests that it comes from “the [uniquely Irish?] custom of wearing a ring on the index finger of your left hand if you are not engaged or married, on the second (long) finger if you are engaged, on the third (ring) finger if married, and on the little finger if entirely disinclined”& Collins English Dictionary gives examples of the phrase in use, sometimes to mean postponed or ignored.

But no real help as to why.

Links
Example Sentences Including 'long finger'
Long finger
Phrase finder
BBC News: When did the middle finger become offensive?