[citation needed] They achieved worldwide fame with their international hit songs "Radar Love" in 1973, which went to number one on the Dutch chart, reached the top ten in the United Kingdom, and went to number thirteen on the United States chart,[7][8] "Twilight Zone" in 1982, and "When the Lady Smiles" in 1984.

[9] He later did this again for the Dutch version of Fern Gully and for Hanekam de Rocker (together with his bandmate George Kooymans ).

In 1994, he sang lead vocals and played alto flute on the Ayreon song "Sail Away to Avalon", the single from the latter's debut album, The Final Experiment.

In 2019, Hay released an album with musician JB Meijers (The Common Linnets); For You Baby, which contains Latin-flavoured cover versions and includes Blue Bayou, a duet with Danny Vera.

On 5 February 2021, the band's manager announced to the Dutch press that their active career was over due to George Kooymans' serious illness.

In 2001, Hay left The Hague and moved back to Amsterdam, although he now divides his time between the Netherlands and Curaçao, where he hosts a radio show.