says Jon Snow ("celebrity cyclist and CTC president") who "lost two seriously good bikes in a year".
http://www.bikebiz.com/news/32752/Thousands-of-unclaimed-bikes-pile-up-in-London
There is no doubt that many bikes are recovered each year and not re-united with owners. One reason will be that many people don't bother to report bikes stolen!
Some police forces make more effort than others to match found bikes to bereft owners.
If the police had one of Mr. Snow's titanium Condors in custody would they give up after failing to find a "security marking"?