Last week I flew First on AA DFW->LHR, continuing in business / Club Europe on BA to CDG. The oneworld site suggests my long haul should have given me access to BA's first lounge in LHR's T5, but they denied me access and sent me to the business lounge. When I asked for clarity on the long-haul flight rule the agent said it'd have worked if I had flown on BA rather than a oneworld partner.