Alpha 13 the only reason I knew it was cancelled was because my dad who's company had booked him on that flight called me to say that BA had emailed him to say the flight was cancelled. Then about 20 mins later he got a text from BA. I know that up until 8pm the flight was still showing as operating.
My dad's moved his meeting to early tommorrow evening so has been rebooked on a later flight and looking at the loads on the first two flights I am guessing most of the other customers have contacted BA themselves.
So it wasn't due to any inside knowledge it was down to my dad telling me.
If as you say you are a gold card holder my advise to ensure this never happens is contact the BA exec club gold line and ask them to check that the contact info they have on record is correct.
My dad, who is a gold card holder had this problem with no text messages during disruption in the past. He found that the information on his exec card record was wrong. Even though you enter a mobile number at the time of booking the system automatically pair up the booking with your exec file and puts the info on file as your primary conatct. So if this is wrong then no message will be recieved.
You could also check if you have time with the Aviance/BA ticket desk staff in EDI or you will probably find the ticket desk at LCY more helpful, that the number on your booking has been captured.
What my dad has started doing is after the booking has been made he goes into manage my booking on BA.COM checks the booking and enters his mobile number. It only takes a minute and since then he has had no problem. Contact BA also send out emails automatically when a flight is cancelled asking you to contact them
When it comes to why the flight is cancelled. I can only guess that the problem is with the aircraft in Southend where Flightline the operators on behalf of BA Cityflyer are based.
Skipness One Echo for your information Cityflyer are not a poor relation as they use the same booking and notification system as mainline services.