I realise I'm very late to this topic, but I only came across it recently, and joined PPRuNe specially to reply.
I'm the chap who wrote the (woefully inadequate) page on the Smiths Flight System, referred to by EGHH. I've since read an awful lot more about it, and replaced the page with a complete section. If there are any howlers, please let me know! The new section starts here:
The First Autopilots
In answer to 40&80: I have manuals for the Comet 4 that cover the Smiths Flight System. Not full detail; not the complete Smiths Instruments manual, but chapters in the Comet 4 Systems Manual, Operations Manual and Flying Manuals. Do let me know if you're still looking for more information. I might be able to help.
In answer to 411A: by really, really amazing coincidence, John A. Gorham, the British Smiths Instruments engineer who was project manager for installing the Military Flight System in the Vulcan, moved to Lockheed as Assistant Chief Engineer on the L-1011. Among other things, he proposed and managed the autopilot development.
So, 411A's post was not so far off-topic after all!