In the early 1970s, Slesser joined Beckett, replacing original singer Rob Turner, who had been killed in a car accident. Beckett released one self-titled album in 1974, produced by Roger Chapman of Family.
Slesser then joined Back Street Crawler and its successor band, Crawler, for the balance of the 1970s. Following the demise of Crawler, Slesser joined the band Geordie in 1980, after its lead singer, Brian Johnson, joined AC/DC, subsequent to the death of Bon Scott.
In 1981 after the departure of Paul Di'Anno, Slesser was asked to audition as the lead vocal in Iron Maiden (as mentioned by Steve Harris on the Iron Maiden The Early Days DVD.
In 1983, Slesser joined the band Charlie as lead vocalist. Slesser was featured on the band's US hit single "It's Inevitable", and the related album
In 1984, Slesser toured Europe, Japan as a vocalist with the Michael Schenker Group.
Slesser continues to tour relentless.
Now 50 years since he performed with Paul Kossoff Terry is back in the driving seat singing all the classic songs he helped create with Kossoff along with some Free anthems.
...The Band Plays On.