While not a lost bag, my son recently flew from MCO to LGW with Virgin following the end of a 9 month Disney Cruise Line contract with 3 large suitcases, 1 of which was new and arrived with a large tear across the front, it seems there were 3 or more other passengers with similarly damaged bags from the same flight.
Not knowing the correct procedure he just left the baggage hall without filling in the necessary claim form and then complained to us, to be honest not sure if it was damaged by the airline handling at MCO, or the TSA, who have in the past opened the TSA padlocks to check his bag, then placed the padlock in the bag and zipped it up, unlocked!
I then, on his behalf, took the matter up with Virgin, provided comprehensive details and pictures and within 3 weeks was requested to contact their bag supplier and the next day a brand new suitcase of equal size and almost quality was duly delivered.
Just goes to show that sometimes the airlines do the right thing and to give VA credit, it was all handled by email within the time frame and with a satisfactory outcome for a lowly Y passenger.
For once a happy ending.