Kavan Ratnatunga writes:

According to the International Bank Note Society (IBNS), An essay ("essai") or trial is any piece generated during the design phase, leading tothe final banknotes. When compared with the final Banknote there might be significant variation and the essay may bear no resemblance to the final issue. 1This study is focused and restricted to Ceylon banknotes designs which were never used to issue a banknote, and ignores color trials, color separations,specimens etc of issued notes.

An essay which is most often unique and therefore by definition extremely rare are popular among those collecting banknotes as an investment. Individuallythey didn't seem numismatically interesting, but as a collection, they tell an interesting background to the designs of banknote issue. Most are notproperly cataloged and Auction Catalog Listings are the only source of information on essays. The Banknote essays sell for upward of £500.

Since around 2008 Spink of London has been listing a large number of Ceylon essays from the archives of Bradbury Wilkinson (BWCL) and Thomas De LaRue(TDLR). These essays got into the Numismatic market after TDLR took over BWCL in 1986. Spink has granted permission to use their images in this website,subject to the condition that a link is put to the original auction lot archive listing. This has been done to about 100 lots from 23 Auctions.

To read the complete web page, see:
Essays of Ceylon BankNotes 1927-1978 (http://notes.lakdiva.org/essay/)