The packages that get deployed to the Primary Hub wasp namely:
uimhome, mps, adminconsoleapp and uimesdplatelemetry
had their .war files deployed to the correct directory
but none of the war files had expanded to create the relevant subdirectories for the webapps.
Deactivated the Primary Hub wasp and manually expanded the war files using unzip utility.
The unzip created the relevant directories under the webapps folder.
Activating wasp after that allowed it to start up okay.