He was born at Springvale near Castlerock, County Londonderry, in 1810, educated at the Belfast Academy and Glasgow University, and was called to the Irish Bar in 1833.
[1] Greer entered public life in the wake of the Great Irish Famine which, together with a drop in agricultural prices, compounded the poverty and insecurity of tenant farmers.
[2][3] With James MacKnight, editor of the Londonderry Standard, William Sharman Crawford MP, a progressive County Down landlord, and group of radical Presbyterian ministers, in 1847 Greer formed the Ulster Tenant Right Association.
When Downhill Castle, owned by the Tory landlord Sir Harvey Bruce, was burned down in a malicious fire, Greer made a name for himself by waging a successful legal campaign against the attempt of the landlord-controlled county Grand Jury to place the cost of its rebuilding on the local taxpayer.
While supportive of the legislative union with Great Britain, Greer was not prepared to enter into the pan-Protestant unionist alliance urged by the sometime Presbyterian Moderator, Henry Cooke.
[7] With even Orangemen supporting the tenant right (forty were expelled from the Order for declaring for Greer in then still open balloting)[4] he edged out the Tory Sir Harvey Bruce, 2,339 votes to 1,676.
Two years later, standing for the Liberal Party (a United Kingdom union of the Radicals, Whigs and the anti-protectionist Tory Peelites)[9] his vote dropped from a third to a quarter of the ballot, and the Conservatives regained both seats.