A colleague working for a government office contacted the government travel provider for clarification. A rep from the provider contacted QF and this was the response:
Terminal 3
Qantas has a lounge agreement to use the British Airways Lounge in Terminal 3 as this is the terminal where all Qantas Flights depart from.
Access to this lounge is for all eligible Qantas Club members as well as Gold and Platinum Frequent Flyers and Chairmans Lounge Members.
The standard Lounge Access policy conditions apply – ‘must be travelling on QF/BA operated flights’. One guest allowed (except CL members who are allowed 2).
As this is a British Airways Lounge, not a Qantas Lounge, the child policy is different. The child age for this lounge is up to 12yrs. (whereas for Qantas owned Lounges it’s up to 18yrs).
Partner Agreement with BA
A partner Agreement is also in place with British Airways which means Qantas Club members are entitled to use the BA Lounges however the agreement is only for the ‘Terrace Lounges’ and ‘Executive Club Lounges’. The lounges which are in Terminal
5 are not these types of lounges – they are ‘Galleries Lounge’ therefore Qantas Club members are not entitled to these lounges.
To find the location of the British Airways Terrace and Executive Club Lounges, please follow this link
www.britishairways.com/travel/ecbenftloungelist/public/en_au
To access a partner lounge, the customer needs to present their Qantas Club membership card or Platinum / Gold Frequent Flyer card plus boarding pass and must be travelling onwards that day on a flight marketed and operated by BA. One guest is also allowed access as long as they are travelling with the member.
Terminal 5
As Qantas does not depart from Terminal 5 there is no agreement for Qantas Club members to use the BA lounges located in this terminal.
The partner agreement is also not applicable based on the above therefore access to the British Airways Lounges located in T5 would only be for oneworld members (Sapphire and Emeralds which is equivalent to Qantas Gold and Platinum Frequent Flyer) and the standard oneworld Lounge Access policy applies – must be travelling on a oneworld marketed and operated airline. One guest allowed also travelling on a oneworld operated and marketed flight.
Complete and utter rubbish, as far as I'm concerned. According to the document with the link provided above, Qantas codeshares on nine BA flights ex-LHR and
departs from T5. Yet they are not entitled to lounge access.