Yes I gathered I might, I had a senior moment and forgot I'd posted before !
Have since got around to trying out the gun on an ordinary flash adapter and it doesn't work. The adapter works on a non-dedicated gun but not on the Sigma/EOS. It would appear I need a dedicated adapter ?
I think you will not find that answer here as most of us will not be familiar with EOS systems let alone flash for EOS.
Ask me anything about Hasselblad flash units and I can help you.
For your information Hasselblad had three different flash systems:
A ring flash from the 60-70 era. It fits 50 bay and 63 mm threaded lenses.
Power from a Braun or Metz generator pack.
A special adapted Metz 45 CT unit with built in SCA adapter.
And finally the Hasselblad D40 unit only to be used as TTL/OTF unit with cameras that support that system.
All three units are no longer available other than offers at eBay etc.