Originally Posted by
Swanhunter
Typo corrected!
The odd thing is that after I challenged not being given an invite the agent stated I was entitled to access, but no guest (as they had been told Star Gold is the same as Voyager Gold). This despite the Star Alliance website stating it is me plus one guest when on a Star Alliance operated flight. If i was entitled to access as Star Gold, then the lounge must have been considered as Star Gold lounge.

I've never been denied lounge access on the basis of a lounge not being operated by the relevant airline. LH, OS, LX to name three have given me contract lounge access across Europe on the strength of Star Gold. That said, there was no Star Gold sign outside the WDH lounge.
Yes, I agree that it seems odd, but I still believe the problem is that this is most likely not a *G lounge, just a contract lounge. Probably, the lounge has an agreement with SAA that they allow Voyager Gold members in without guest and - by extention - also *G without guest, not on the strength of it being a *G lounge, but as per the contract between the airline and the lounge operator. According to the *A website, the lounge is only a *G lounge if it is signposted as such:
Star Alliance Gold card holders and one guest, have access to any lounge around the world that is identified with a Star Alliance Gold lounge sign when departing on a Star Alliance flight, no matter which class of service they travel in. Just look for the Star Alliance Gold sign outside the lounge and present the ticket for your same-day Star Alliance flight, your boarding pass and your frequent flyer programme card featuring the Star Alliance Gold logo. Guests must enter the lounges with an eligible Star Alliance Gold member and must depart on a Star Alliance member airline, but may travel on a different flight.
Not trying to be pedantic, just trying to understand why you were denied entry.