They played their first gig at The Compasses in Egham, Surrey, with Jon Jeary on vocals and Ian Bennett on bass.

In 1992, they signed their first record deal, and after adding vocalist Damian Wilson to the group alongside guitarists Karl Groom and Nick Midson, bassist Jon Jeary and drummer Tony Grinham, produced their first commercial recording, "Intervention," which was released on a Dutch progressive rock compilation album.

Threshold took a break before their next effort, during which time Morgan and then-drummer Jay Micciche left to form Mindfeed.

Wilson was unavailable for their next album, so former Sargant Fury vocalist Andrew "Mac" McDermott, joined to record Clone and would remain with them until 2007.

The band released Dead Reckoning which spawned a music video for an edit of the song "Pilot in the Sky of Dreams".

In 2009 the band released a limited edition eight-disc singles box set, including previously unreleased b-sides and brand new re-recordings of old demo songs released in other forms before, including Smile at the Moon, (which was debuted live on the 2009 Essence of Progression Tour), Shifting Sands, Half Way Home and Fist of Tongues.

Glynn Morgan, the band's former vocalist from 1994 to 1996 replaced Damian Wilson for the album Legends of the Shires released in September 2017.

[6] In 2024 Threshold released newly remixed versions of their first four albums Wounded Land, Psychedelicatessen, Extinct Instinct and Clone on CD and vinyl formats.

[7] The band promoted the remixes with the retrospective Threshold Through Time Tour where they performed songs from all twelve of the studio albums.