How to get full (read AND write) access to your Google Calendar in Thunderbird:
- Install the Lightning calendar add-on for Thunderbird.
- Install the Google Calendar Daemon application / service.
- Configure said application (and ensure that you install the Windows service – I had to do this manually, it wasn’t done as part of the installer!).
- Add a new calendar to Thunderbird and point it to your Calendar as published in the Daemon.
- Job done!
Now I can modify my calendar via a rich client application. Sadly it doesn’t work for Windows Calendar as this application seems to think that it’s a read-only calendar. Haven’t yet tried it with Outlook.