>Doh. I'm not sure what you were suggesting in the 3rd option (changes in the UserControl or in the consuming form?) but just the mention of routed events made me realise that my UserControl Clicked event was not routed! Once that was changed so that it bubbled I could handle it as an attached event anywhere up the tree....

You got it. I would use PreviewMouseDown on the ListBox.

>I've not familiar with the ItemContainerGenerator class. AFAIK I've never had occasion to use it (but of course with WPF until you know about it you don't know whether you've needed it or not :-})

It allows you to define a custom class for the contained items. That can come in handy at times.

>I now currently dithering over whether to go for specifying a Key or a DataType in the DataTemplate.......

I frequently go DataType (But then I use a lot of treeviews, so it's needed when you have different data types in the treeview.)