It is uncertain whether John McIlhaggart appears in the 1862 list in which there are several clan Johns but no McIlhaggart. In the period July-October 1872 he was living at 101 Charles Street, South where he was a tenant paying a yearly rent of £7.3s.0d, due on Monday in each week. The tenure of the tenancy, which was the same as that of the other tenants on the same plot of land, was described as "Weekly tenant, tenancy determinable on Monday in any week". It appears that this 'Parcel of Ground on the West side of Charles-street South, Sandy Row', was up for sale. It was 'Lot 3' so presumably it was to be auctioned. The description was, "(s)ituate in the town, parish and barony of Belfast and county of Antrim, with the Houses and Premises thereon in Charles-street South and Glenburn Alley, held under lease for lives renewable for ever, dated 30th July, 1839, at the yearly rent of £20. 6s. 0d". On the page (10) on which John McIlhaggart's name appears there are twelve names in Charles Street and four in Glenburn Alley though there may well have been further names on adjacent pages. In the Court records on findmypast there are three references to this 'Lot' which all appear to be the same.
As no John McIlhaggart appears in the Griffith Valuation for 1862, and presuming that John in 1872 would have been a married man, he may well have married before 1865-70 and so have been born before, say, 1845. In my clan indexes I have no such marriage. A John whose dates do fit, who by 1881 was using the spelling McIlhaggart, was married to Mary Stewart (as McIlhagar!) but by 1862 had moved to Greenock, Scotland, so couldn't, one would have thought, have been living in Belfast in 1872. There is however one rather remote, though unlikely, possibility. This John did indeed move to Scotland in 1862 - we know this from the places of birth of his children - but clearly did not settle to work in Greenock immediately, and in 1881, when his wife and family were in Greenock, he was working temporarily in West Ham, London! Did he also temporarily return to Belfast for work in 1872 and live for a time at 101 Charles Street, South? If this be the case, then from my knowledge that he was born in Ballycloghan, it also raises the possibility that he was after all in the 1862 Griffith Valuation (presumably just before he left for Scotland), listed there as John McElhagan.