Thanks K Morita - that was really useful, I searched for Minamoto Tetsuo and found another sword with a slightly different mei but a very similar style of carving:
https://www.liveauctioneers.com/en-gb/item/85976960_wwii-Japanese-army-officer-s-sword
As above it is signed Higo Minamoto Tetsuo Saku which seems like a good match? and they studied under Moritaka Yasuhiro - who Klaus has kindly provided more information in an earlier post.
However searching for Terada Yoshimitsu brought up another sword from this Forum:
That sword is dated to 1981 which is much later than other swords I've seen though.
In the thread Joe (SwordGuyJoe) was able to provide more info on the smith:
And a reference from Markus Sesko's Index of Japanese Swordsmiths:
After all that I'm not 100% certain on who the smith was, whether it was Terada Yoshimitsu or Moritaka Yoshio or another separate person?
They were born just 2 years apart but the younger studied under the other which I imagine is a close age range for student and smith but might be common for all I know.
Thank you Klaus, Uwe, Thomas, Steve and K Morita for all your help.