Unable to install El Capitan: "No packages were eligible for install"
During installation of El Capitan I receive the error: "OS X could not be installed on your computer. No packages were eligible for install."
I am presented with the option to restart, after which the computer enters the installer again and I am shown the same error. Holding down the option key during reboot gives me the option to enter the OS X installer or the Recovery disk. From the Recovery disk (version 10.11) I am able to use Disk Utility to verify that everything is in order with the hard drive. Attempting to use the Reinstall OS X option fails and I am given the message: "An error occurred while preparing the installation. Try running this application again." Repeated attempts have shown the same error.
The laptop is a mid-2009 MacBook Pro (previously) running the latest version of Yosemite (10.10.5).
Ideally I'd like to either continue with the installation of El Capitan or return to the version of Yosemite already installed on the laptop. At the moment the laptop is unusable. I have a time machine backup of Yosemite I could revert to if need be.
Anybody else experience this problem? Any tips would be greatly appreciated.
MacBook Pro, OS X El Capitan (10.11), Mid-2009