The signiture is now there online to look at and print out, it never used to be , but thats if they bother to get one
The best thing of all is that the royal mail no longer accept any claims for missing parcels if the item was sold on ebay! ( we have been told this from the man in the post office over the phone from them, and also from many sellers having it happen to them on the powersellers forum on ebay )
When/if they do accept a claim for loss they will only pay you an amount that you can prove the item cost you as the seller (not the buyer), if you can not prove the cost they will not pay out anything.
For example, buy a rare model engine for £2.00 , resell it for £200 they will only pay out the £2.00 (if you have a recipt) , even with added royal mail insurance that they desperately try to sell every time you post something, they will not pay more or cover ebay sold items.