I've just heard about someone who's had a trip to Spain cancelled by BA - apparently with no offer to route the passenger via Madrid an onward on Iberia.
I thought the two carriers co-operated?
Now, in the last year I had bookings cancelled by easyJet and Ryanair because of schedule changes, but any customer who thinks that "upgrading to British Airways" makes any difference to how one is treated in such a situation should think again because BA's treatment of the customer in the case cited above is no different to what happened to me. I.e., all we got was a refund.