Green’s Dictionary of Slang

tipsy, half-drunk.

1834		Westmorland Gaz. 19 Apr. 1/3: They admitted they were ‘half-slewed’, and gave the money to the crimp.
1845		Bradford Obs. 7 Aug. 6/1: Two men were found, one quite drunk, the other ‘half-slewed’.
1854		Preston Chron. 16 Sept. 5/1: Sturdy wiry fellows [...] being ‘half-slewed,’ they were as ripe for a shindy as Paddy himself at Donnybrook Fair.
1862		N. Devon Jrnl 29 May 5/1: Charles hancock [...] described the prisoner’s state as a ‘little sprung,’ ‘half-slewed,’ etc.
1872		Western Times 14 May 3/4: Were you drink or sober? — Neither one nor t’other — I was half slewed.
1881		Staffs. Sentinel 21 Sept. 3/4: Defendant, who said he liked to go to work sober and not ‘half-slewed,’ promised to do better.
1901		Lichfield Mercury 29 Nov. 8/3: I was half-slewed when I went there.
1916		Western Gaz. 8 Dec. 6/4: Gale must have been the worse for liquor when he returned on the Sunday evening [...] in the morning he was ‘half slewed’.
1925		Hull Dly Mail 17 June 5/2: Prisoner [...] said ‘a chap who was half-slewed offeered him the two cheeses.
1931		Tamworth Herald 11 July 6/5: Bolding was ‘half-slewed’.