Here's an extract from Michael Hogben's A-Z of Antiques and Auctions book.
If the contents of an estate includes a specialist collection - for example, eggcups, inkwells or cruet sets - these may be put together as a job lot and catalogued as such. This does not mean that the auctioneer thinks that these items are worthless; rather, the saleroom is trying to target a specialist collector who will buy the whole lot in one go.
A sleeper is an item of value that has been overlooked by the auctioneer. For example, amongst a shelf of blue-and-white china there just might be an early piece of Royal Worcester; that shelf of Art Deco collectables could just contain a small piece of Clarice Cliff.
Read Michael Hogben's biography
