1908 1 Nov. 1251 ‘On my own’ (by myself) became ‘on my Pat Malone’ and subsequently ‘on my Pat’ a very general expression nowadays.
1930 12 Mar. 47/1 On your pat now, aren't you? When did the old man go away?
1966 ‘L. Lane’ 110 On me tod, by myself. An alternative phrase is on me pat.
1978 R. H. Conquest 10 He rode, on his pat, close on 800 miles.