Blakes 7 Wiki

Sector 4 was a star sector, apparently on the fringe of Federation space. The Federation lost and regained control of the sector around the time of the Intergalactic War.

The Federation launched a massed attack on the Liberator in Sector 4 while it was en route to Exbar. Exbar itself may have been in the sector.

Saurian Major's full co-ordinates were 'star sector four six point two one' - as even deep galactic space was only classified as Sector 12 it seems unlikely it was in Sector 46, and the full co-ordinates may be for a specific Sector 4 location. (A: Time Squad)

The Pacification Programme allowed the Federation to re-take control of the planets Luba, Porphry Major and Helotrix, which it had lost at some unknown prior time (possibly during the War itself). After these re-annexations the Federation apparently controlled the majority of the sector. (D: Traitor)

Tarsius was recaptured at around the same time so it may also have been located here.