A fan of Agatha Christie, Jennifer Grant paid just £100 for a beaten-up leather case at an auction in September 2006. The case was firmly locked, and no clue was given as to the contents.
Grant simply wanted the case as a quirky talking point - one last mystery left behind by the creator of Miss Marple and Hercule Poirot.
Three and a half years on, Grant gave in to curiosity and had two builders crack the case, inside which was a strongbox. The contents included 52 gold coins (35 sovereigns and 17 half-sovereigns), and an oval brooch and a ring, both set with diamonds.
The ring, marked C M M is thought to have been the engagement ring of Christie's mother Clara Margaret Miller, and the brooch is believed to have been hers as well. Christie refers to both in her autobiography.
John Benjamin from the BBC's Antiques Roadshow estimated that the valuable pieces have an intrinsic worth of around £20,000, but the memorabilia element of their close association to Christie could see them fetch five times as much.
Christie is the most published novelist in the world with 4 billion book sales to her name, so the discovery of a significant piece of her memorabilia - such as an unpublished novel found by Christie collector John Curran - causes great excitement.