Vapor Deploy sh: composer: command not found

I am trying to deploy my Laravel app using Vapor and when I do vapor deploy staging I get an error.

Although Composer is installed globally I get the following:

Building project...
==> Validating Manifest File
==> Copying Application Files
==> Harmonizing Configuration Files
==> Setting Build Environment
==> Executing Build Commands
==> Running Command: composer install
sh: composer: command not found

  The command "composer install" failed.

  Exit Code: 127(Command not found)

  Working directory: /Users/tomcreasey/Sites/******/.vapor/build/app

  Output:
  ================


  Error Output:
  ================
  sh: composer: command not found

I cannot find any troubleshooting surrounding this. Has anyone got any suggestions?