Almost immediately after Orac's arrival on the Liberator the ship is taken over by the System.

(And as for the shortly-to-be-named Liberator being in the vicinity of a space battle and the London - Orac set everything up. Why else would Blake, Avon, Jenna and Vila have ended up on the same prison ship? Orac needs a pilot for the Liberator, a computer expert is useful, as is someone with Vila's practical experience - which would include manipulating computers, and Blake the rebel would, perhaps, become more reliant on Orac than the Federation.)

So Ensor left the System - not necessarily as a rebel - with the basics of Tarriel cell technology, and developed it within the Federation. Thus Orac is able to take over Zen, because their structures are compatible.

Any comments?

Jacqui