Scully was a native of Aharney in Tullamore.[3][4] He had two brothers and six sisters: Ned, Michael, Nance (Hanlon), Mary (Garry), Rose (Cleary), Margaret (Henry), Lily (Elizabeth McDonnell) and Emily (Hanlon). All bar Emily predeceased him.[4] He studied philosophy at UCD[5] and theology at the Oblates Scholasticate in Piltown County Kilkenny.
During the 1960s, Scully trained the Belcamp College boarding school team in Dublin to three Leinster Schools' Football Championships.[1] He led Offaly to the final of the 1968–69 National Football League (their first), the Leinster Senior Football Championship title (their third) and then to the 1969 All-Ireland Senior Football Championship Final (their first since 1961), having only taken over that year (though he would have trained any Offaly players living in Dublin).[1][6]
Scully departed for South Africa in 1970 to teach mathematics in Johannesburg.[1] However, apartheid did not suit him and he moved to England instead.[1] While in England he lived in both London and Manchester.[6] He there became involved in the Lancashire GAA.[2] By 1988, Scully had become Director of the Irish Centre in London.[1] He established a day centre for the elderly and encouraged the older Irish to mix with the older English and the older Europeans living there.[1] In May that year, RTÉ's reporter Leo Enright was in Camden Town and Scully spoke to him on camera.[1][7] He was selected as Offaly Person of the Year in 1989.[6]
By 2018, Scully's eyesight had deteriorated.[1][6] Based in later life in the House of Retreat in the Dublin suburb of Inchicore, Scully heard confessions and ministered to the sick.[6] He died in Dublin of COVID-19 on the morning of 7 April.[1][3][8] He was one month short of his 90th birthday.[1][6] His death occurred at St James's Hospital.[2] He had been in hospital for less than a week and had spoken over the phone during those final days.[1]