He rose to fame in the mid-1960s, with an exuberant live act which included wearing tight breeches and billowing shirts, in an Edwardian style popular amongst his peers at the time.
Following several hits in the UK, he became a Las Vegas lounge singer and his image quickly changed. He was known for his overt sexuality in the 1960s, before this was as common as it became in subsequent years. Ladies would swoon and scream, and in 1968, starting at New York's Copacabana night club, some would throw their panties on stage. Soon after, in Las Vegas, they started throwing hotel room keys.
His early hits include:
- It's Not Unusual (1965)
- What's New Pussycat?, written by Burt Bacharach for Woody Allen's What's New, Pussycat? (1965)
- Thunderball, the theme for the James Bond film (1966)
- The Green, Green Grass of Home (1966), his most successful single, which became associated with his native Wales, despite being written about the USA
- I'll Never Fall In Love Again (1967)
- Delilah (1968)
- Help Yourself (1968)
- Without Love (1969)
- She's A Lady (1971)
His recording career was revived in 1987 with his first major hit single in over a decade, A Boy From Nowhere, taken from the musical Matador. Following this, he started to record with a younger generation of musicians. These recordings included:
- Prince's song Kiss (1988, with The Art of Noise)
- Burning Down The House (1999, with The Cardigans)
- Baby, It's Cold Outside (1999, with Cerys Matthews of Catatonia)
- Iggy Pop's song Lust for Life (1999, with The Pretenders)
- Mama Told Me Not To Come (2000, with Kelly Jones of the Stereophonics)
- Sex Bomb (2000, with Mousse T)
- Tom Jones International (2003)
He continues to tour and record.