VanguardLH wrote...

I then deleted these messages. Or rather, I tried to. All Outlook does is to
cross a line through them. I cannot get them to actually delete from Outlook. It
was only when I logged into Gmail webmail that they disappeared.

That's how IMAP works. Your e-mail client is staying in sync with what
is up on the mail server. You haven't yet actually deleted the message
up on the mail server. You only made it *eligible* for deletion in your
e-mail client (which you could undo). You either wait until the next
mail poll when your e-mail client synchronizes up with the mail server
(so items *marked* for deletion in your e-mail client will also get
deleted up on the server) or you use the Purge option in your e-mail
client to force an update on the mail server rather than wait for the
next mail poll.

I tried this but it didn't happen. Only when I logged into Gmail and deleted the
messages did it reflect that in Outlook.

I then tried creating and replicating my existing message base but I couldn't
get it to work. I tried creating labels in Gmail but they didn't replicate in
Outlook.

What does "couldn't get it to work" mean?
What does "replicating my existing message base" mean?

I have in th Local Folders, a number of folders which contain messages that I've
sorted according to what they're about.

I was trying to replicate that, but I couldn't get it to work. (and I now
understand why after your explanation about the types of message stores, I
s'pose you call them).

I then created some folders in Gmail but they didn't appear in Outlook, even
after mail polls.

I don't do labels in Gmail. I access Gmail primarily through my local
e-mail client, not by using their webmail client where is the only place
you can define Gmail's own labels.

Yes, and it was in both Outlook and Gmail that I was trying to create the
sub-folders. But it didn't work.

Your multiple hosts are polling the SAME account. With IMAP, each one
will sync to reflect what is currently on the mail server. You'll have
to explain just WHAT is different in one e-mail client (on your desktop)
using IMAP to your Gmail account versus what is different in the other
e-mail client (on your laptop).

They should be the same. As I'm at work I can't confirm this.

Whatever, thanks for the help folks. I'll continue to have a play with it.