Publications (including this website) sometimes refer to messages from the SDS being received at Hannington Hall (or even Coleshill). Although Hannington did serve for a period as admin HQ for the SDS has anyone ever come across specific information that the final destination for SDS messages came to Hannington / Coleshill?
Unless there is specific information isn't it more likely that they went directly to SIS Communications HQ at Whaddon Hall ?(as Geoffrey Pidgeon states in Secret Wireless War, p.90). The SDS grew out of the wireless network of the SIS 'Home Defence Organisation'. SIS jealously maintained control of intelligence traffic - only reluctantly giving SOE independence in this respect in 1942. Messages from SDS outstations went to IN stations based at army HQs and to the intelligence staff based there. From there, anything other than of purely local interest could be sent to Whaddon either by secure phone line or via the SIS Special Communications Units discretely parked at the HQs. The main purpose of the SCUs was to pass on information filtered by SIS (including ULTRA traffic) to whichever military command seemed to need it and therefore it seems logical that they could also pass information gathered by SDS back to Whaddon. As there was no means of passing information gathered by SDS to the Auxiliary Units then there seems little point in including Coleshill in the information chain?
Looking at the Jones SDS system map the routing appears to show that Coleshill, Berkshire had 3 direct feeds which could connect to 5 or more inner control stations.
There is nothing showing Hannington Hall being on the Network. However we know that the SDS used Hannington Hall, (Wiltshire) as Administrative Headquarters during Major Pethericks time. Perhaps the map was produced later.
It certainly appears from the Jones Map that Coleshill acted as a sort of regional hub (as there seems to be elsewhere). However, if the final link in the network was controlled by SIS and was to an SIS facility then there would be no need for it to be mapped onto a map of Aux Unit Signals responsibilities - and good security reasons for not doing so. Unfortunately, I suspect it will take something of a minor miracle to get any proof!