Born in Edinburgh, Scotland, Jeffrey began playing at an early age, but suffered a career-ending injury.

This resulted in an offer to coach the men's soccer team, a position he held for 27 years.

[2] The United States Soccer Football Federation selected Jeffrey to coach the United States men's national soccer team at the 1950 FIFA World Cup just two weeks before the competition after Erno Schwarz declined the position.

Jeffrey led the U.S. team to its historic 1–0 win over England in the 1950 World Cup, considered one of the greatest upsets in soccer history.

[6] Jeffrey died of a heart attack while attending the NCAA soccer meetings in New York.