Its a long shot - but TiGr titanium bike lock lost 17 May 2013 on a Thameslink train from Bedford to Brighton (arrived Brighton 0918). Due to the size I had put the bike lock on the floor of the train which is where I left it
So could have been found anywhere down to Brighton or possibly on the way back as well! Been to Lost Property (multiple times) at Victoria, City and Charing Cross which seem to cover the multiple train companies and locations it could have been found.
Long shot.....

Long shot.....