bookmarks-> imported bookmarks also displays old speed dials, but these seem to be from a far earlier sync, my guess would be from about 2-3 years back.

Those are the ones imported from other browsers in your computer. By default Opera imports some data from the default browser during the installation.

therwise my current bookmarks/speeddials are only available from the link you provided.

Then it seems that something is wrong with synchronisation in your Opera.

Have you tried logging out from Sync and then login again?

Do you see anything under Bookmarks and Bookmarks > Other Speed Dial?

in that link, the right click context menu gives me the option to add a folder to my speeddial

Nope, this is an option to add the page you are on to your speed dial.

Also, the link you provided gives me a choice of two machines, one being my old system with its bookmarks, one being the new one

Under bookmarks? Which version of Opera were you using before?

in that link, the right click context menu gives me the option to add a folder to my speeddial. this however has no effect afaict, opening the context menu again however, gives me a new option of removing the folder. weirdly, I added the folder "forums", however now the context menu gives the option of removing the folder from speeddial for all other folders in there (my "daily" folder, "awesome" folder etc). none of these folders appear on speeddial.

Also, the link you provided gives me a choice of two machines, one being my old system with its bookmarks, one being the new one. There is no obvious way to import the old bookmarks that I can see.

Yes! Everything is there!

It means that your data is synced.

Have you checked the tab menu for opened tabs, bookmarks > other speed dials for speed dials and so on?

Now is there a quick way of transferring everything back or will I have to manually open all pages and re-add them? The FAQ seems silent on this and I found no obvious way of doing it from that archive...