I used to get an reference to a minimised window in the 'panel' (?) at the bottom of the screen.

This has stopped happening, ctrl+tab will cycle through open windows though.

Sorry I don't know the correct names for the various parts of the Plasma screen.

Any ideas?

OK, bit the bullet and deleted the whole panel.

Then created a new one which came along with a System Tray and a Task Manager.

By looking at another system I learned that I was missing a Task Manager.