"Named after Disraeli's novel Lothair, published in I870. It was another political novel in which real personages appeared in very slight disguise" (John J. Marshall, Belfast Telegraph, 03/03/1942). The publication of Lothair was something of a sensation at the time, but the novel has not aged as well as some of Disraeli's earlier works, such as Coningsby (1844) or Sybil (1845).
As regards Marshall's reference to real personages appearing in very slight disguise, the title character, Lothair, is loosely based on the 3rd Marquess of Bute, John Patrick Crichton-Stuart (1847-190), a Scottish aristocrat who, as an infant less than a year old, had inherited an enormous fortune derived from his father's development of Cardiff as a port exporting coal and iron.
"Resolved that on the application of the Owner, the new street leading from Atlantic Avenue to Oceanic Avenue be named Lothair Avenue". (3rd December 1879). The minutes of the Town Improvement Committee 1 April 1880 note approval was given to Samuel Lawther for “amendment to 21 houses in Lothair Avenue”.