Green’s Dictionary of Slang

lord mayor v.

to swear.

c.1895		C. Osborne [perf. Herbert Campbell] ‘Dada’s Baby Boy’ 🎵 She stands on her filbert, and gracefully falls / Jerusalem, how she Lord Mayors.
1910		‘Doss Chiderdoss’ ‘Gifted’ Sporting Times 9 July 1/4: There was Bill, a dear old pal o’ mine, he could ‘Lord Mayor’ a bit, / And he could put a lot of ginger in it, too.
1914		Billy Merson ‘Gay Cavalier’ 🎵 ‘Foresooth gadzooks and strike me pink’ / He couldn't Lord Mayor ’cos the gay Cavalier.
1932		‘P.P.’ Rhy. Sl. 13: Get me a ‘Joe Blake’ for Tom Tucker’ and no ‘Lord Mayoring,’ or there’ll be a ‘bull and cow’.
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 11: The Lord Mayor: To swear.
1961		(con. 1930s) D. Behan Teems of Times and Happy Returns 207: ‘Easy, Jack,’ said Da. ‘Mind the lord mayorin’ in front of him.’.
1971		J. Jones Rhy. Cockney Sl.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.