It's usually not just the item itself, but the history attached to it. For example a medal issued in the Crimean War or Boer War to a soldier is valuable. The same medal accompanied by a letter of commendation by a senior field officer to a senior staff officer at Horseguards (Whitehall) plus a letter home to his mother, say, from the man the medal was awarded to, describing a ceremony (at Sebastopol or Witwatersrand) in which the medal was pinned on his tunic by Lord Cardigan or Lord Roberts. This documentary corroboration, known amongst dealers and collectors as 'Provenance', makes the medal much more collectable and fetches a premium at auction. Add to that the rarity value. The Victoria Cross was first cast from a Russian cannon captured at Inkerman in the Crimean War. Few were actually issued in that campaign. For a guide Watch 'Antiques Roadshow' or any of the other collectables programmes on BBC TV/Yesterday Channel, or even 'Dickens Real Deal' on Channel 3 in the afternoon. There's a mine of information out there, latch on and maybe you could profit!