It is sad, but inevitable that there will be cases where people clearly have strong motivation, yet have fallen at one hurdle or another. I know that if I had not got the offer I Friday, I too would have been totally gutted, so I can empathise with your torture in having to wait another year. Hopefully that persistence and tenacious struggle will shine through and pay off.
Gliderrider - you are clearly not doing anything wrong to have got to the final day, but I assure you from my dealings with BA and IAG in a number of capacities that the business is entirely proper, upstanding and non-discriminatory on age and every other factor. The financial equation makes sense for them in the same way that it would for a ex-military DEP at your age as well, so don't be disheartened - try again.
I certainly made full use of the "scuttlebutt" method of gleaning anything and everything I could about the process and BA through any contact I could get my hands on - Michael - your are clearly going to get there someday (though I waited longer than you for this scheme to come about!)
There are obviously a wide range of people selected who are all "good guys and gals" whom the interviewers are prepared to sit next to for 12hrs+ each day, who have the prerequisite skill set. There will always be more than places available - at least you know what you are facing next year.
I particularly admire our fellow successful applicant who is now facing 46+ years in the flight deck at BA - more than half the present history of the company from its origins in the 1920s! Without being patronising, that deserves some congratulations, as I'm not sure many, and certainly not I, had sufficient maturity and skill sets at that age!