Green’s Dictionary of Slang

1. Calcutta; thus ditcher, an inhabitant of Calcutta; also attrib. [the Mahratta Ditch, built by the East India Company in 1742 to protect Calcutta from the Mahratta tribesmen, it ran for 8km (3 miles) but the work was never finished].

[1758		Derby Mercury 17 Feb. 1/3: The Lands within the Moratta Ditch all round Calcutta [...] and six hundred Yards all round the Ditch, I will give entirely to the [East India] Company].
1839		Asiatic Jrnl & Mthly Register Jan. 39: Few readers of the Asiatic Journal will require to be told that, in Bengal, [...] ‘the Ditch’ is the soubriquet bestowed upon Calcutta by those who desire to disparage the city of palaces.
1843		Morn. Post 6 Dec. 2/1: All this time, we of the Calcutta ditch are as quiet as a ‘setting [sic] duck’.
1850		India Sporting Rev. XII 69: The carrion in question [i.e. ‘high’ venison] was destined for the Calcutta market, and on my expressing curiosity, mingled with wonder, as to what class of Ditch gourmands revelled in such offensive and poisonous luxury, I was informed it was much appreciated by the wealthy Calcutta Baboos.
1854		Delhi Sketch Bk 1 Aug. 92/2: Yet I behold / This swinking city on the Ditch’s shore / With satisfaction.
1861		Times of India 20 Dec. 2/7: Poona has a far better chance [...] of becoming the seat of the Supreme Government. It must be borne in mind that this question will have to be settled at home, where Ditch interest goes a very little way.
1863		Times of India 24 Oct. 3/3: The ‘public!’ The Calcutta howlers, the second rate merchants, the gambling speculators, and semi-insolvent trading community of that filthy ditch.
1870		Times of India 8 Mar. 4/1: Never was a civilized community more given up to be plundered by the natural enemies and leeches of society than that of Calcutta [...] life in the Ditch is becoming more and more impossible.
1886		Yule & Burnell Hobson-Jobson (1996) 319/2: DITCH, DITCHER. Disparaging sobriquets for Calcutta, and its European citizens. [Ibid.] 537/2: MAHRATTA DITCH, n.p. An excavation made in 1742, as described in the extract from Orme, on the landward sides of Calcutta, to protect the settlement from the Mahratta bands. Hence the term, or for shortness ‘The Ditch’ simply, as a disparaging name for Calcutta.
1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant.
1934		Letters of an Indian Judge to an English Gentlewoman 114: Our jails are full, our Courts are working overtime over this ridiculous business of non-co-operation which will get us nowhere but into the Ditch.

2. the Suez Canal.

1858		Liverpool Mercury 26 Aug. 2/7: the remarks of Sir Robert Stepheson, C.E., on the Suez Ditch, as he terms it [...].
1878		Eve. Teleg. (Dundee) 11 Jan. 2/6: Nothing can disturb their equanimity so long as there is no interference with the Suez Ditch.
1887		Manchester Eve. News 13 May 2/4: Beresford [...] ridicules the idea of England wasting her resources in endeaviouring to defend a ‘ditch’ like the Suez Canal.
1904		Cook Co. Herald (Grand Marais, MN) 14 May 7/3: Engineers in charge of Ditch at Suez.
1915		Wkly Teleg. 1 Feb. 4/1: headline] The Threatened ‘Ditch’ Wonders of the Suez Canal.
1923		Aberdeen Jrnl 5 Dec. 5/4: Britain is as broad as the four seas [...] You feel it whenever you [...] enter the ‘Big Ditch’ at Suez.
1984		LaBarge & Holt Sweetwater Gunslinger 201 (1990) 236: Ditch – nickname for Suez Canal.

3. (N.Z.) the Tasman Sea, which divides New Zealand from Australia.

2003		McGill Reed Dict. of N.Z. Sl.
2016		D. Whish-Wilson Old Scores [ebook] ‘[A] new mob of bikies, not from over East but even worse, from across the fucken ditch, is muscling into Perth’.