Major-General Sir Thomas Aiskew Larcom, Bart, PC FRS (22 April 1801 – 15 June 1879) [1][2] was a leading official in the early Irish Ordnance Survey.

He later became a poor law commissioner, census commissioner and finally executive head of the British administration in Ireland as under-secretary to the Lord-Lieutenant of Ireland, a position the government of the day was eager for him to take.

With the rank of lieutenant he led the day-to-day operations of Survey headquarters by 1828 under Lt-Colonel Thomas Colby and established a meteorological observatory in Dublin.

At the completion of the Survey's six-inch maps in 1846, Larcom joined the Irish Board of Works.

[1] The longest-serving under-secretary (1853–1868), Larcom had a distinguished career in his adopted country and acted with an impartiality that won him respect from all parties.