I don't know how it is now but the assistant stage manager had to understudy several parts. You had to be ready to go on at any time if the actor couldn't make it to the play. I didn't think anything of it.
-- Glenn Ford
   
Glenn Ford   Name:
Glenn Ford
Type:
Actor
Nationality:
American
Birth:
May 1, 1916
Death:
August 30, 2006
https://www.nutquote.com/quote/Glenn_Ford