Get to know West End theatre understudies, swings, and alternates

Sophie Thomas
Sophie Thomas

Although a West End cast will often perform up to eight times a week, the cast isn’t complete without understudies. Sometimes you may not see an understudy, a swing, or an alternate, as they can be additional cast members who are called upon at a moment's notice to step into a role. However, West End understudies are crucial to making sure the show goes on!

If you’re wondering what an understudy is, when they perform on stage or who has previously been an understudy, read our guide to the often unsung heroes in a cast.

What is an understudy?

An understudy is an actor that’s cast in a production to cover a performer if they are unable to attend a performance, or to take over a role if a performer is unable to continue in the role. An understudy may have to be nearby to the theatre for each performance in order to jump in or take on a role that they haven’t performed in months! Sometimes, cast members from years gone by may reprise a role for a one-off performance if they're called upon to do so. You never know who you're going to watch, but that's what makes live theatre so exciting!

Understudies are often cast in a show as a member of the ensemble, meaning an understudy will have to balance two or more parts in one show and learn multiple "tracks." A track is a path taken by a performer during a show that stays the same, regardless of who is in the role. That way, if an understudy, swing, or alternate fills in a person on stage, they take on that "track" rather than during their own thing. Tracks help everyone on stage!

Different types of understudies

In a show’s cast, there will often be different categories of understudies who are all able to step into a lead role at just a moment’s notice. We’ve broken down what it means to be a 'understudy', a 'standby', and an 'alternate'.

Understudy: Cast in a show for every performance, an understudy is typically in the ensemble of a production, who will take on the principal role when the lead actors are unavailable. When an understudy is covering a larger role, a swing will usually take the place of the ensemble member to cover them.

Swing: A swing is a cast member of the company who is not employed in one specific role, but learns multiple tracks so they can cover many people. Occasionally, a swing may have to perform a "cut track," which means they'll be doing the jobs of two or more people as one person. Swings do not perform in every performance unlike an understudy who is usually in the ensemble.

Standby: Similar to a swing, a standby will not appear in all performances of a production they are working on. However, a standby will only learn one role to cover for a production, typically the lead roles. Standbys must be ready to cover the lead role at any moment.

Alternate: An alternate is someone that's cast in a show in a specific role, but will not perform every date. Typically, alternates are guaranteed at least one show per week. Many shows use alternates in their cast: The Phantom of the Opera has an alternate Christine, while Dear Evan Hansen employs an alternate Evan. If the main cast member isn't in a performance, then typically, the alternate will assume first rights to go on.

Should I see a performance with an understudy?

Yes! Understudies are guaranteed to deliver an exceptional performance every time they’re on stage, so while they may be covering a role, you’ll still see a world-class show. You may also see an understudy as a lead role in another show, so you’ll want to see these rising stars in action.

Originally published on

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