Green’s Dictionary of Slang

1. (also lumper, lump of bread) the head.

1858		A. Mayhew Paved with Gold 169: ‘You won’t know your “lump o’ lead” when I’ve finished with you,’ cried Merton, referring to his antagonist’s head.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict. 367: Lump of lead, the head.
1884		Sporting Times 6 Dec. 1/1: Went to read and write. Got lump of lead like Parish oven. North and south knocked on one side. I suppose smashed .
1903		Bulletin (Sydney) 20 Aug. 29/2: During the day the suspected crank tramps up and down one of the exercise yards and answers inquiries from passing prisoners concerning his ‘lump of lead,’ [...] or any other slang term for his poor addled head that their sense of humour suggests.
1914		N.Z. Truth 31 Jan. 2/8: I went up the apples and pears [...] to the shovel and broom (to my room), put my lump of lead on the weeping willow [...] and ploughed the ocean deep.
1915		W. Gippslang Gaz. (Vic.) 10 Aug. 3/7: My cobber Bill fell down beside me with a hole in his lump of lead.
1928		M.C. Sharpe Chicago May: Her Story in Hamilton (1952) 132: Lump of lead – head.
1927		Eve. Herald (Dublin) 30 Nov. 6/4: Cockney bricklayers seem to have a quaint language of their own [...] lump of lead — head.
1937		L. Lane Me and My Girl I i: all: Gingerbread? bill: Me lump o’ lead! all: Lump of lead? bill: Me Uncle Ned! all: Uncle Ned? bill: Oh, me ’ead.
1944		Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3 194/1: Lump of Lead, The head.
1948		Sun. Times (Perth) 25 Apr. 35/2: Mince-pie for eye; lump of lead for head; twist and twirl for girl; storm and strife for wife.
1960		J. Franklyn Dict. of Rhy. Sl. 93/2: Lump of bread The head.
1963		L.F. Freed Crime in S. Afr. 105: His ‘lump of lead’ means his head.
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxvi 4/1: lumper: Head, from lump of lead.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1981		P. Wright Cockney Dialect and Sl. 105: Lump o’ lead ‘head’.
2002		Pete’s Aussie Sl. Home Page 🌐 lump of lead (2): the head.

2. bread.

1902		Worcs. Chron. 3 May 3/1: The rhyming slang for bread is ‘Lump o’ Lead’.
2002		Pete’s Aussie Sl. Home Page 🌐 lump of lead (1): bread.

3. a hangover, i.e. a head n. (4a)

1960

J. Franklyn Dict. of Rhy. Sl. 93/2: Lump of lead The head [...] in England specialized to refer to the head on the morning after the night before – ‘I woke up after the wiv a marf like a carsey an’ I couldn’t lift me lump-o’-lead orf da tiwillow to git at the fisherman’s.’.