The short version is that we got most (but not all) of the Diana Rigg episodes available at the time. The long version's a little more complex.
We have seven boxsets, each containing two disks, which are labelled:
1965 One and Two
1965 Three and Four
1966 One and Two
1967 One and Two
1967 Three and Four
1967 Five and Six
1967 Seven and Eight
And that lot appears to cover all of Season 4 (sans four episodes), all of Season 5, all of the very short Season 6, and the first episode of Season 7.
1966 Three and Four (though I've just ordered it)
At some point, we'll have to get our hands on:
1968 One and Two
1968 Three and Four
1968 Five and Six
1968 Seven and Eight
and while this 1962/1963 is tempting, they appear to be about to release a better version.
It's tricky working out what we've actually got, because Amazon list them as "1965 Box Set 1", but the the actual box identifies itself as "Files One and Two". And Amazon are showing cover art from the disk boxes, which is different cover art from the overall boxset box.