Lambert spent two years working as repetiteur and assistant kapellmeister at the :de:Schleswig-Holsteinisches Landestheater und Sinfonieorchester|Schleswig-Holsteinisches Landestheater in the North German town of Flensburg. There he came into contact with the new music of the 1960s and 1970s. In 1976 he attended Darmstadt composers' course when György Ligeti was lecturing there: Epitaph was selected for performance. The Park Lane Players gave performances of the Fantasy Trio and the Canzonetta for Clarinet & Piano. As a result of attending the Gulbenkian course for composers and choreographers in 1977, led by Robert Cohan, he wrote Ephialtes for Scottish Ballet, Invention and Maxims, Hymn, Riddle for Jonathan Burrows and the Spiral Dance Company. While serving his apprenticeship in Germany, he also worked at the Wexford Festival Ireland ; in 1977 he joined the music staff of the Royal Opera House Covent Garden,. His Piano Quartet Emplay was the winner of the Humphrey Searle Chamber Music Competition and played twice in the finals at the Purcell Room in 1983. The Chamber Concerto was performed by Lontano at the 1984 Bath International Music Festival. The Mass for Four Voices was performed at the Huddersfield Contemporary Music Festival and broadcast on BBC Radio 3. In the 1980s and 1990s Lambert was involved in the Royal Opera's developing outreach program around the country which explored innovative ways of composing operas alongside children and amateurs : this resulted in several opera projects including The Treasure and a Tale, performed at the Snape Maltings and The Button Moulder, a specially commissioned work for teenagers adapted by Lambert from Ibsen's Peer Gynt. This production travelled to the US. The chamber opera Caedmon based on a play by Christopher Fry was produced by the Royal Opera at the Donmar Warehouse in May 1989 with Christopher Gillett in the title role. All in the Mind was commissioned by W11 Opera, also to Lambert's own libretto, and performed at the Britten Theatre in London. Several works have been performed in the Newbury area in Berkshire, England, where he now lives. He is musical director of the Newbury Chamber Choir and in 2013 formed a group called The Music Troupe which has since performed regularly at the annual in London. In 2014 The Music Troupe mounted productions of Six Characters in Search of a Stage, The Inarticulate Burr, Stillleben, and The Catfish Conundrum. There followed Opera With a Title, The Cloak and Dagger Affair and The Parting, The Oval Portrait, The Art of Venus and Apollo's Mission.
