If you find something by the roadside which you perceive should have an owner but has no identifying marks so you can return same personally to its owner, hand it into your local Police Office as found property and ensure you get a receipt.
Store the receipt and ensure that you dig it out again on the expiry of 6 months.
Return to the Police Station with said receipt and request previously lodged item which is now (lucky for you....) unclaimed by its rightfull owner.
Its now yours legally ....... 
Unless someone at the station takes a shine to it. 

PMSL
A mate of mine is on motorway maintainemce, when there is an accident they are the lucky guys that allways get the call to go clean the mess up.
Unless of course a lotty load of whisky rolls over, so what happens, all the forces vans, estates and 4x4 suddenly turn up to help, most of the vehicles drive away with thir suspention bottoming out (Illegel to drive with an overloaded vehicle of course)
Then what happens, motorway maintainece get a call to clean up loys of broken glass and card board.
Then when the insurance inpector/assesor turns up at the secure compound to survey the reclaimed salvage, there is nothing there.
Result, there needs to be a police inquirery about the missing goods.

:-/
