If I’m using the Desktop version of Manager, is the data stored anywhere except on my laptop (which has just been stolen)
Manager desktop edition works completely offline.
your accounting data will be stored only on your local hard drive which is the application data folder shown under Preferences…
but you can always sync this application data folder to any online storage like dropbox or google drive and also manually create a backup. so if you did backup your data, you can import it later on any new computer with Manager installed.
Thanks, I feared as much! Wish I’d set up a proper backup now 
or gone cloud…