Not absolutely sure but I think the first Avro 748 had a Smiths SEP 1 when I first flew the prototype G-ARAY during conversion training in 1967. I do know that the VIP Avro 748's for the Royal Australian Air Force were fitted with the Collins FD 108 system and that Avro's had a difficult job interfacing the Smiths autopilot system with the Collins FD system.