Thanks for the quick reply.
I think on reflection that I should do a concise version of the above, because it's too long and has some irrelevant information in it. That will be in the next post. But to answer your questions:
- BA did say we were delayed by 8 minutes, but that is - I'm sure I remember this right - not true. We sat on the tarmac for ages. I guess it's possible we left the gate 8 minutes late (I don't recall), but we did not take off for some considerable time after. The MCT was, if I remember right, 1hr25, and the schedule had 1hr35 in it. I arrived around 45 minutes before the MSY flight took off, but couldn't get through immigration, baggage, security in time.
- The first rebooked flight would not have got me into MSY in time. The ORD-DFW flight was delayed, meaning just that I would have missed DFW-MSY, and been overnight at DFW instead of ORD. Final arrival time would have been similar.