Roland, as we never practised with the owners I am not entirely sure what would have happened. AFAIR the Mk 1 would have had the weapons enabled at some point but this was not a crew procedure. In otherwords it was fit and forget.
The Mk 2 was fitted with a SWEC3 (?) and that might have incorporated the SEP to which you refered. It was 'safer' (?) but took longer to operate which was not a good feature during the attack.