Every major organisation that deals with the public has a lost property department, which exists to look after items left behind by visitors, and which attempts to reunite the two. Lost property comes in various shapes and sizes. Common items are umbrellas, wallets, bags and spectacle cases.
If you lose a useful item, forget it. The human race are, in general, not inclined to hand your item in to a lost property department. This fact applies mainly to useful umbrellas - the sort you pay a reasonable amount of money for; the type of umbrella that does not initiate its self-destruct sequence at the first sign of bad weather. It follows then, that you should make all of your umbrellas, bags, spectacle cases and wallets look as ridiculous as possible, because if you lose them, you are far more likely to get them back, since nobody in their right mind would want to keep them.
When dealing with lost property, it is vital to make sure that the item(s) are not ticking. If you find any unattended property that sounds suspicious, you should leave it alone, and ask a local law enforcement official to deal with it. This can have embarrassing consequences as the owner of an abandoned item returns, only to discover that the anti-terrorist squad have reduced the suspicious package, in fact a brand new grandfather clock, into a million tiny fragments scattered over a wide area.