NEIL
your knife is an ERINOX by ROTHLISBERGER of BARAU
Rothlisberger was the only other OFFICIAL maker of knives for the swiss army since 1921....although only in 2 years...1956 and 1957. they also made officer style knives of which yours is a nice example
here are two youtube videos showing Rothlisberger knives...one soldier and one officer similar to yours (both from my collection)
I hope this was helpful. cheers. Dave Arnold