Their staff will make every effort to do what Imperial, BOAC and BA always used to do as standard?
Don't you mean "Should have done"? I recall making an on-line connection at the old LHRT4 in a queue for Security. One of the only times I actually had a F class ticket. I asked the BA person if we could be expedited as, due to their late inbound flight, I didn't think we were going to make our connection. No, was the reply, get in the queue like everyone else. I said I wasn't impressed and I was unlikely to choose BA again, to which she commented - I don't know why you idiots fly with us, I don't.
Alliances are always trying to describe and convey the benefits of travelling with them, when in reality all of the benefits are to them. You don't always get the best connection, you get the connection they want you to have. There isn't even a consistent level of service. While BA can be good, they often aren't, and AA and IB are much much worse.