Summary
When travelling on a
oneworld marketed and operated flight:
BA Gold (oneworld Emerald)

Members (plus one guest) have access to all available and accessible
oneworld first and business class departure lounges
BA Silver (oneworld Sapphire)

Members (plus one guest) have access to all available and accessible
oneworld business class departure lounges
BA Bronze (oneworld Ruby) and BA Blue

Members are not granted access according to their tier but may still have access to departure lounges depending on their class of travel that day.
Taken from the
oneworld website: Emerald or Sapphire level top-tier members of
oneworld airlines' frequent flyer programmes have access to almost 550 departure lounges across the globe, no matter which
oneworld airline you are flying. In all cases, lounge access eligibility is based on:
Departing carrier - you must be flying on your next onward segment, on the same day, on a flight marketed and operated by a oneworld member airline,
AND
Frequent flyer tier status - you must present a current frequent flyer card equivalent to oneworld Emerald or Sapphire status,
OR
Class of travel (see below) - you must produce a First or Business Class boarding pass for the journey's international segment on the same day.
Guesting privileges qualified by status
With regard to
oneworld lounges, once again the guesting rules are relatively straight forward.
BA Gold (oneworld Emerald)

Members may invite one guest into a
oneworld first class or business class lounge. Both the member and guest must be travelling on a
oneworld operated and marketed flight, though not necessarily on the same flight or same carrier.
BA Silver (oneworld Sapphire)

Members may invite one guest into a
oneworld business class lounge. Both the member and guest must be travelling on a
oneworld operated and marketed flight, though not necessarily on the same flight or same carrier.
When it comes to the extra provisions BA offers its own customers at its own lounges, the rules are slightly more complicated
BA Gold Guest List members

- BA Concorde Room:
Member flying BA First plus two guests.
- BA owned First lounge:
Member plus two guests when all are flying BA irrespective of class of service
- BA owned Club lounge:
Member plus two guests when all are flying BA irrespective of class of service
- BA Departure Spa treatments:
Member plus two guests when all are flying BA long haul
- BA First pre-flight dining:
Member flying BA First plus two guests
- BA Club pre-flight dining:
Member flying BA Club World plus two guests
- BA Arrivals lounge:
Member plus one guest (both flying BA long haul)
Concorde Room Card holders

- BA Concorde Room:
Member plus one guest when flying BA. The CCR card is not valid for entry to any other lounge
BA Gold members

- BA Concorde Room:
No access by virtue of status but may be afforded access qualified by class of service
- BA owned First lounge:
Standard oneworld rules apply
- BA owned Club lounge:
Standard oneworld rules apply
- BA Departure Spa treatments:
Member has access when flying BA long haul. No guests
- BA First pre-flight dining:
Member has access when flying BA First. No guests
- BA Club pre-flight dining:
Member has access when flying BA First or Club World. No guests
- BA Arrivals lounge:
Member has access when flying BA long haul and further access to the inner Concorde Room when flying BA First. No guests
BA Silver members

- BA Concorde Room:
No access by virtue of status but may be afforded access qualified by class of service
- BA owned First lounge:
No access by virtue of status but may be afforded access qualified by class of service
- BA owned Club lounge:
Standard oneworld rules apply
- BA Departure Spa treatments:
Member has access when flying BA First or Club World. No guests
- BA First pre-flight dining:
Member has access when flying BA First. No guests
- BA Club pre-flight dining:
Member has access when flying BA First or Club World. No guests
- BA Arrivals lounge:
Member has access when flying BA Club World or First and further access to the inner Concorde Room when flying BA First. No guests
BA Ruby and Blue members

- BA Concorde Room:
No access by virtue of status but may be afforded access qualified by class of service
- BA owned First lounge:
No access by virtue of status but may be afforded access qualified by class of service
- BA owned Club lounge:
No access by virtue of status but may be afforded access qualified by class of service
- BA Departure Spa treatments:
Member has access when flying BA First or Club World. No guests
- BA First pre-flight dining:
Member has access when flying BA First. No guests
- BA Club pre-flight dining:
Member has access when flying BA First or Club World. No guests
- BA Arrivals lounge:
Member has access when flying BA Club World or First and further access to the inner Concorde Room when flying BA First. No guests
Lounge access overview | Access qualified by status | Access qualified by class of travel | Lounge database