When established fiddler Thady Casey heard Crehan play in a pub (having taught himself initially), he offered to tutor him - as a result, Crehan learned the fundamentals of fiddling from Thady, and learned stylistically from both him and his brother, Scully Casey, who was also a respected fiddler.
[3] Crehan was encouraged by the folk revivals of the 1950s and later, and involved himself with Comhaltas Ceoltoíri Éireann, at one point serving as president of its Clare branch.
He made extensive use of double-stops, and music writer Barry Taylor suggests this may result from the influence of his friendships with uilleann pipers Willie Clancy and Johnny Doran.
[1] A number of tunes currently popular within the Irish Traditional Music community were written by Junior.
A further and even better-known example is "The Mist Covered Mountain", inspired by Mount Callan which can be seen from his home in West Clare.