It's a crew and metal assist from IB, to help BA with their tight resourcing on both. I don't think it is seen as a permanent arrangement but it will be a bit of a hybrid (e.g. CE food served by IB staff, cabin crew announcing "We welcome home our passengers who live in London" delivered in a Spanish accent). A bit like the Titan leases, in a way. If anymore bits of hardware fail then we may see further flexible responses from other directions.