These were produced as part of the release packages for the first few Games Workshop stores. Like many "limited editions" they were later repurposed as needed.
The Birmingham store was opened on September 5th 1981, but this fiugure looks later. It later appeared on the 1987 Original Dwarfs as Captain Fendor and as Dwarf in Plate Armour in US Blisters.
The Manchester store at the Arndale center opened on April 17th 1982 replacing an earlier Manchester store at St James Square. The Rabbit Assassin and the Broo Assassin are clearly based on the same model.
You were expecting an Owl perhaps? The Sheffield store opened on May 22nd 1982.
The Nottingham Store Opening was on 10th October 1982 (WD 34). This Dwarf was later released on the Original Dwarfs Flyer in 1987 as the Robin Hood dwarf.