Born in Dublin, McNally first played football for a small local club, St. Finbarrs.
He was a right back and began his professional career in the League of Ireland with Shelbourne in 1954 and then moved to Luton Town F.C.
One of the Forest scorers that day was Roy Dwight, who was later carried off after breaking his leg in a tackle with Brendan.
Roy, who died in 2003, was the cousin of the singer/songwriter Sir Elton John.
Brendan later on played for Dunstable Town and managed non league Chesham United where he gave future England international Kerry Dixon his first start in senior football.