Thanks plunet and CWS. It was the "baggage portal" that wasn't working insofar as whenever I hit the continue button it kept taking me back to the same original screen when I pressed continue again and so forth. Thanks for the baggage line number CWS. I called and got through to an incredibly helpful agent (Golden ticket for him) within two minutes, who gave me a reference number and then by logging that number in, I see that my bag has been found and is awaiting delivery to me.

As an aside, while the flight and cabin crew were aware that no hold bags had been loaded except the gate checked bags, they did not inform the passengers of this, as was confirmed when I heard the inflight manager say so to the ground agent as soon as the door was opened at Edinburgh.. This I thought was poor show from BA as passengers were then waiting at a carousel at Edinburgh for bags that were never going to appear yesterday evening........