The internet contains many references to the public career of Patrick McGoohan. His Theatre days and 1950/1960's British film and TV career are often only vaguely known. This site, and my supplemental sites noted above, offer fuller details of those times.
I have endeavoured only to use original archive material or references which are supported by two expansive biographical articles:
1965 by 'Drummond Enterprises'
1985 by Barbara Pruett.
Theatrical Career
1947-1952 - Sheffield Repertory
1948 - St. James' Theatre, London
1951 - Theatre Royal, Bath
1952 - Royal Court, Liverpool
1952 - Arts Theatre, London
1952 - Theatre Royal, Windsor
1952-1953 - Midland Theatre Company, Coventry, Loughborough, Nuneaton, Netherton
1953 - Bristol Old Vic
1953 - Old Vic, London
1954 - Theatre Royal, Windsor
1954 - Q Theatre, Richmond
1954 - Embassy Theatre, Swiss Cottage
1955 - Garrick Theatre, London
1955 - Duke of Yorks Theatre, London
1956 - Lyric, London and Hammersmith
1959 - Lyric, Hammersmith
1985 - Wilbur Theatre - Boston, U.S.A.
1985 - Royale Theatre, Broadway, N.Y.C.
These sites are only representative of my personal collection and enthusiasm.