[3] Briley was later signed to George Martin's Associated Independent Recording (AIR) group of companies and went on to become an important part of the London studio scene as an arranger, vocalist and sought-after session guitarist.
[4] He also had a brief stint as bassist/guitarist of the British progressive rock band Greenslade, touring with the group and playing on their 1975 album Time and Tide.
[4] Briley moved to New York, where he found work as a touring and session musician for numerous artists, including Meat Loaf, Julian Lennon,[6] Bonnie Tyler, the Modern Jazz Quartet, Engelbert Humperdinck, Lulu, Mick Jones, Donna Summer, Cliff Richard, Olivia Newton-John, the Hollies, Tom Jones, Ian Hunter and Albert Hammond.
Briley signed a deal with Mercury Records as a solo artist in the early 1980s, going on to release three albums under his own name.
Briley has received orchestral commissions, and has written songs for such artists as Céline Dion, *NSYNC, Dream, Michael Bolton, Mietta, Kenny Loggins, Pat Benatar, Jessica Andrews, Five Star, Jeff Healey, Rebecca St. James, Nana Mouskouri, Willie Nile, Gregg Allman, Night Ranger, David Hasselhoff, Patrick Swayze, Michael Monroe, Chaz Bono, Peter Tork, Nikki Webster, Hope Partlow, Natascha Sohl, Ballas Hough Band, Phil Stacey, Orianthi, the Maine and Barry Manilow.