He was fortunate to have as a playground the semi-rural surrounds of the Royal Canal, the nearby Botanical Gardens and the Victorian urban landscape which helped to fuel his artistic imagination and love of history.
One such endeavour, a balsa wood model of his imaginary concept for a then proposed Roman Catholic cathedral in Dublin, is today on view in the Tara's Palace Museum of Childhood in Powerscourt House in Co. Wicklow.
Liddy had initially wanted to be an architect but disliked the way architecture was developing in the early 1960s, especially in his native Dublin, and decided instead to join the national airline, Aer Lingus, in April 1963.
[2] Using his skills of self-taught architectural draftsmanship and general artistic ability, Liddy started to paint and draw scenes from the urban landscape[3] in an attempt to bring attention to the uniqueness and charm of Dublin before those places disappeared forever.
Starting in 1982 and running until 1989, Liddy's weekly column in The Irish Times, called "Dublin Today," featured a pen and ink sketch of a building or place of interest in the city and was accompanied by a description of around 400 words.
Taking early retirement from Aer Lingus in 1994 he turned his attention full-time to painting, drawing, exploring and writing about the historic buildings, scenic places and exciting new developments in his native city.
Liddy was married in 1976 to Josephine Murphy (born Lyre, County Cork) and has three children: Anne Marie, Pádraig and Brendan; and two grandchildren: Rosemary and Senan.