Green’s Dictionary of Slang

a Liverpudlian; thus Scousers, a collective name for Liverpudlians.

1943		Liverpool Eve. Exp. 4 Dec. 4/2: The Army nickname for a Liverpool man is ‘Scouser’.
1945		Liverpool Eve. Exp. 11 Aug. 3/4: The name ‘scousers,’ given to Liverpool-born people, has become known the world over during the war.
1959		Times 8 Dec. 13/6: Their [i.e. Liverpool workers’] catarrhal speech would identify them as ‘Scousers’ wherever English is recognized.
1966		T. Keyes All Night Stand 24: ‘Yay, scousers,’ shouted Gerry.
1979		(con. 1940s) G. Stewart Leveller 57: The firemen on this ship were mostly hard cases: Liverpool Irishmen, (scoucers).
1980		J. McClure Spike Island (1981) 16: ‘If you live in Liverpool,’ some Scouser once said, ‘then you must either laugh yourself sick or burst into tears.’.
1999		N. Cohn Yes We Have No 103: Scousers were sharp, Scousers had wit.
2007		Indep. 1 June 20: If he was a Scouser he would have been well ‘made up’ over so many spondulicks.
2012		D. O’Donnell Locked Ward (2013) 122: he was a genuine Scouser [...] although he had adopted a RP (i.e. posh) accent.