I have never seen a version of Thunderbird that acted like you describe. If you start typing in the address field it will show a list of suggestions. Do you have the Contact Sidebar turned on in the Write window? If not press F9 when you have a Write window open.

Thanks for the quick reply! Unfortunately I'm not too clued up on TB. Could it be some add-on that did this in the earlier version?. The F9 command seems not to allow bulk address insertion for forwarding as was previously available.

bulk address insertion... do you mean like a mailing list?

Yes, but not fixed, just individual selections to forward an email to.

the list your talking of should never have appeared until you typed something in the box.

The contact pane on the left, hold the Ctrl key while clicking on those you want to include. Then when your done, click the to or BCC or whatever button.

That works, thanks! Don't know why the usual has gone. Much appreciated.