Not sure if this is your man but from Woodard Database in Tewkesbury there is this from Tewkesbury Register Newspaper September 1921:-
Birthday Celebrations - Messrs. Nicholas A Mann Of Tewkesbury And William E Mann Of Rock Ferry, Cheshire, Celebrated Their 79th Birthday. Both Cabinet Makers. Joined 5th Lancashire Artillery In 1865 Both Ulster Loyalists. Grandfather Former Nicholas Mann Of Tewkesbury. Brother, John Collins Mann, Oifficial Gt. Northern And Ireland Railway
and in November 1888:-
Death - 04/11/1888 at Newry in Ireland: Robert Mann, late Sgt. Major of Essex Regiment aged 58. Eldest son of late Sgt. Major William Mann also ex-56th Regiment. He was a Crimean War Veteran who had been port of Sebastopol and the Indian Mutiny; he had 6-7 medals; Nicholas Mann was still in Tewkesbury and had helped found the Volunteers with Captain Moore. He was the grandson of Nicholas Mann