Green’s Dictionary of Slang

gatch n.

[‘Probably Irish ‘Gáitse’ - a showy gesture. (Dinneen) and ‘Gaatch’ (aa long as in car) - an affected gesture or movement of limbs, body or face. (Joyce) and note spelt ‘Gache’. (Murphy)’ S. Beecher Dict. Cork Slang (1983); note SE gait]

(Irish/Cork) a swaggering walk.

[Ire]L. McInerney Glorious Heresies 73: That was an easy strut. Chest out, shoulders back, the heavy gatch of a lad whose balls hung low.
[Ire]L. McInerney Rules of Revelation 41: Gain his trust, creep closer till you’re walking beside him. Copy his gatch.