Your Iberia Plus Gold card lets you access any Iberia VIP lounge around the world if your flight is operated by Iberia Group and/or marketed by Iberia. Your guest can only access it if his or her flight meets the same conditions and/or the guest has a boarding pass from a oneworld company for that day.
When your flight is operated by the Iberia Group, you can access the lounge with children under 18 travelling with you (except at the airport in London).
Plus, when you travel on a oneworld flight, you and your guest will have access to some 550 VIP lounges around the world. Your guest must have a boarding pass from a oneworld company for that day. For more information and conditions see here.