Etheridge began his career at hometown Fourth Division club Northampton Town. By the time he made his debut for the club during the 1962–63 season, the Cobblers had been promoted to the Third Division. Northampton's ascension to the Second Division at the end of that season further harmed Etheridge's first team chances, with his best appearance tally being 9 league games during the 1964–65 season. He departed the club in February 1966, having made just 17 league appearances and scored one goal in four-and-a-half seasons at the County Ground.
Brentford
Etheridge joined Third Division club Brentford in February 1966 for a £8,000 fee and quickly won a place in the team. A poor 1965–66 season culminated in relegation to the Fourth Division, with Etheridge having made 16 appearances. Etheridge found himself in the reserve team during the 1966–67 season and made just eight first team appearances. He experienced some joy with the reserves and won the 1966–67 London Challenge Cup with the team. Etheridge departed the Bees at the end of the 1966–67 season, after making 24 appearances and scoring two goals during 18 months at Griffin Park.
In the summer of 1967, Etheridge moved to Belgium to sign for First Division club Daring Club de Bruxelles, managed by EnglishmanBilly Elliott. He played in roughly half the club's matches and made 14 appearances and scored one goal during the 1967–68 season. He broke into the team in the following season and 28 appearances, scoring three goals and making appearances in Daring's 1968–69 Fairs Cup campaign. Despite European football, a disastrous season saw the club relegated to the Second Division. Etheridge departed Daring at the end of the campaign, after making 40 league appearances and scoring four goals for the club.
Etheridge transferred to Second Division club Cercle Brugge prior to the beginning of the 1969–70 season. In a one-season stay, he made 26 appearances and scored no goals.
After leaving professional football, Etheridge became a businessman and was a partner in a packaging firm, based in Wales. He was married to Pauline and had two children. Etheridge hanged himself at his home in March 2011, having suffered from depression and made several attempts on his life previously. Etheridge's grandson, Tom Collins, is a rugby unionwinger and full back for Northampton Saints and has been capped at England U20 level.