Robert, I don't know what your experience consists of, nor what employer you were applying to or what their requirements were. It may well be that, individually, you have a case for discrimination, or would have, if legislation was in place to support your claim. I suspect, however, that it would be very difficult to prove as so many factors are involved in the decision whether to employ someone or not.
In a situation where there are far more applicants than jobs, it is inevitable that there will be many disappointed individuals. Some of those may be so disaffected that they will claim discrimination in some way or other - indeed, it's now become pretty standard to have to field several claims of discrimination after any employment competition. The vast majority of these claims are frivolous and unfounded, and stand no chance of support in law.
It is relatively easy to defend the criteria used to select people in most complex professional jobs, and extremely difficult to demonstrate that the sole reason for being denied employment was one specific and discriminatory criterion. If an employer doesn't feel that you fit his requirements, he can refuse to employ you. It's his company, and he has (in this case) several other candidates who may better fit his criteria. If the issue is age, so long as he can show that he has in the past employed people of various ages, I suspect that no case against him would stand. If he has a record, on the other hand, of never employing anyone over, say, 25, there may be a case to answer - if the employer cannot demonstrate that age combined with relative inexperience is a problem. Unfortunately for those who would argue otherwise, the military have demonstrated on several occasions that teaching older pilots is problemmatic, and thus have set their maximum age of pilot recruitment at (funnily enough) 25.
I'm not saying that age discrimination doesn't exist. What I am saying is, even with legislation, it will be extremely difficult to prove, especially as research backs the contention that older pilots are more difficult to train. This will be presented as a safety issue, and once the magic word 'safety' is uttered, all other arguments become secondary.
You may have the financial muscle, determination and stamina to attempt to argue your case through the layers of the legal system - once legislation is enacted. I wish you luck. However, I have considerable doubts of your chances of success. But I am not a legal man. If you'd like a (much) more authorititive opinion of your position, you might like to try and talk to Flying Lawyer, Pprune's own tame legal expert. A short search should find him!
Scroggs