Morrow joined Northern Bank on 20th July 1908 at Head Office. He was of Church of Ireland faith.
On ‘Ulster Day’, Saturday, 28th September 1912, a Lewis Morrow signed the Ulster Covenant at Clones Orange Hall.
Morrow aged 24, whilst based in Clones volunteered and enlisted into the Public School Corps on 11th January 1915. He saw service with the British Expeditionary Force, the Somme in 1916 (Beaumont-Hamel) and in Arras 1917.
Following demobilisation, Morrow rejoined the Bank at Head Office on 2nd January 1918. Transfers followed with Clones (1918), Head Office (1918), Portaferry (1918), Newtownstewart (1920), Ballynahinch (1926), Raphoe (1930), Irvinestown (1933) and Randalstown (1940).