He then moved to the NHL head offices, becoming the director of central scouting, and later took a directorship position in the hockey operations department, which he held until his death.

[5] In 1959, while working for Colgate-Palmolive,[4] he gained employment with the Toronto Maple Leafs after an interview with owner Stafford Smythe, which was set up with the assistance of his former school coach, teacher and mentor at St. Michael's, Father Bauer.

[6][3][7] His duties included maintaining his responsibilities with the Marlies, a Maple Leafs-sponsored team, along with scouting, and working at Smythe's summertime aggregate business.

[8] Gregory was hired in 1967 by the Vancouver Canucks (an affiliate of the Maple Leafs) of the Western Hockey League as head coach.

[5] They also introduced many future stars including Darryl Sittler, Lanny McDonald, Tiger Williams, Ian Turnbull, and Mike Palmateer, during a time which many players defected to the rival league, World Hockey Association.

[9][10][11] He was one of the first managers to turn to Europe as a source of NHL talent, recruiting defenseman Borje Salming and winger Inge Hammarstrom, in 1973, to play for the Leafs.

[3] However, after the Maple Leafs suffered an elimination in the quarterfinal round of the 1979 Stanley Cup playoffs, Gregory was fired by owner Harold Ballard, and replaced with his predecessor, Punch Imlach.

[17] In 2007, Gregory was elected to the Hockey Hall of Fame as a builder, while he was on a hiatus from the selection committee due to ill health.