Andrew Malkin, an ensemble member in the cast of The King's Speech who was also understudying the role of Lionel Logue, has died of a heart attack aged 49, just days before he was due to make his West End debut.

Malkin came late to acting, spending 23 years working in IT before retraining at East 15 Acting School. He graduated from the school's MA in Acting course in 2008.

He was discovered in his digs after failing to arrive at a technical rehearsal on the evening of Tuesday 20 March 2012. It is believed that the time of death could have been as early as the night before.

His agent Niki Winterson, who arrived shortly after Malkin's body was discovered, has said in a statement that he did not appear to have been in any pain and looked peaceful.

A coroner today confirmed that he died of a heart attack due to a pre-existing condition. It's believed Malkin was unaware of any disease.

Winterson described Malkin, who she said had "achieved considerable success in his short career", as a "talented, dedicated and popular actor who will be missed by all at Wintersons and by the company of The King's Speech".

Malkin's theatre credits since graduation have included The National Theatre at the White Bear Theatre, Serve Tea Then Murder for Tara Arts, Shakespeare in the Streets at Liverpool's Unity Theatre, Hamlet, Food for Thought and A Pinch of Salt at the White Horse Theatre and on tour in Germany.

He also understudied four male roles in Bill Kenwright’s touring production of Peter Hall’s Bedroom Farce.

His most recent role prior to The King's Speech, which launched its UK tour from Guildford's Yvonne Arnaud Theatre in February, was in the Agatha Christie Theatre Company’s touring production of Verdict.

Following a regional tour, The King's Speech receives its West End premiere at London's Wyndham's Theatre on 27 March 2012 (previews from 22 March).

A statement from the show's producers said: "Andrew Malkin was a highly valued and very popular member of The King’s Speech company. We are deeply shocked and saddened by this terrible news. We as a company will miss Andy very much indeed, but our immediate concern is for his family at their dreadful and sudden loss."