Yes. . as Toby suggests, this is a small Officers' Mess Waiter's Button to the Connaught Rangers.
The button shown by Toby in his second post (QVC atop Harp surrounded by a large wreath of Shamrocks) is a Mess Waiter's Button to The Royal Irish Regiment.
Though this button went against the norm for Mess Waiter Buttons by being a 'closed' back design rather than the more normal open back (livery style) button.
Generally for the Mess Waiter buttons, the small buttons are circa 16-17mm, whilst the large buttons are circa 25-27mm.
I collect Officers Mess Waiter's buttons, so if anyone has any they want to sell, please let me know.
All the best
Ian