You select them how? (a double click is normally required to "open" an email in a window or tab, although operating system settings can change that) All bets are off if you have the conversations addon installed.

Hi Matt, No add ons installed. I have used both Control and Single Click, and also Shift and Single Click to select multiple messages. Also, when I select the 'Bin' option in the folder view it deletes the message, but also deletes the following message (I end up fishing things out of the bin). The last bit compounds if you hit several times as it continues to delete second emails (if that makes sense)

As for the double-click that is exactly what I would expect but can't see any option to change that

Slightly embarrassed. Was not a Thunderbird issue but a Windows double-click option problem. The radio button was selected giving the impression that it was working but it wasn't. Clicked the apply and its sorted. Frustrating but NOT a Thunderbirad issue