Different Sections in Spooks

[JHyde]

From Harry's Diary we know of a few others:

Section M (conspiracy theories, rumours) - which I think would be fun sometimes and exasperating at others, and
Section X (intelligence and surveillance on MI5 officers). This section was previously headed by Oliver Mace, as I recall. I think, I haven't read Harry's Diary in a while.

We also know that Tessa headed up Section K during the 80s. Whether there was a break in service I am not sure.