A complete guide to understudies in the theatre

Read our guide to what it means to be an understudy in a West End show, as well as the differences between theatre alternates, swings, and standbys.

Every show has a cast. But, in every show, there's also understudies in the production. Theatre understudies, swings, and alternates are a vital part of a company, ensuring that everyone can take breaks and guarantee that the show must go on.

Want to know what it's like to be a swing? Do you want to find out the difference between an alternate and an understudy? Read our guide to theatre understudies, often the unsung heroes of a show.

What is an understudy?

An understudy is typically an actor that’s in the main company of a production. Usually, understudies are part of the ensemble in a show, but can also be called upon to perform on select days if a main cast member is sick.

Understudies don’t always have a lot of time to prepare before going on stage. They're often ready to step in at the last moment. An understudy will often have to be near the theatre for each performance in order to jump in with just a few minutes notice or take on a role that they haven’t performed in months.

As an understudy is in the show, they will have to balance two or more parts in one show. While an understudy may not take on their covered role regularly, they are vital to making sure the show must go on.

Once you’ve starred in a musical, that show will always remain in your mind - That was definitely the case for Steph Parry. In 2018, the 42nd Street understudy was sitting in the wings at Theatre Royal Drury Lane. A few minutes later, she’s on stage as Donna in Mamma Mia!, but how you ask?

The knack of an understudy. Having played Donna years ago, Parry was called upon to reprise the role so that Mamma Mia! could continue. Sometimes, the understudy is needed to make sure the show goes on.

What is an alternate?

Whereas an understudy tends to cover a lead role on an ad-hoc basis, an alternate has scheduled appearances each week. An alternate does not cover any other roles in the show; they only play one character on select performances.

Typically, if a show is on for eight performances a week, an alternate will be on for one or two performances that week, usually sticking to the same schedule. For example, the role of Christine Daaé in The Phantom of the Opera is shared between the main actress and an alternate.

What is a swing?

Swings are an integral part of a company, and sometimes have the hardest part to play. A swing member is someone in a cast who will often learn multiple lead roles and ensemble ‘tracks’ so that they can step into productions in a variety of instances.

Swings do not perform in every performance unlike an understudy who is usually in the ensemble. But, swings can also perform in multiple roles for one production — take Hana Stewart in Six who switched roles mid-show.

What is a standby?

Similar to a swing, standbys will not appear in all performances of a production they are working on. A standby will only learn one role to cover for a production. Typically, standbys cover the lead role. Standbys must be ready to cover the lead role at any moment. For examples, the roles of Elphaba and Glinda in Wicked are played by two main actresses, with both roles having a dedicated standby company member.

Should I watch an understudy in a West End show?

Yes, definitely! 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. Many times, understudies can be in the start of their careers, so who knows, you may be seeing a rising West End star in action. Check out new West End stars making their debuts in lead roles.