Wonnacott, who presented BBC's Bargain Hunt for 13 years and is a former divisional chairman of Sotheby’s, collected items on his travels around fairs while filming for the popular TV show.
He said: “The thrill of finding an item priced at £50 that you knew could go on the sell for £500 was just fantastic.”
The first tranche from his collection will be offered on December 4-5, with other selected items appearing in subsequent Sworders auctions in 2019.
Wonnacott added: “Firstly, it has been really difficult deciding what to sell and what to keep. Space of course is a major consideration and objects with keen family or personal and emotive connections are all in the potential 'keep category'. But, even then, the choices are far from easy.
“Secondly, like one's children, one should never show favouritism, even for objects. But some of the pieces which Sworders will offer are so idiosyncratic and ‘one-off’ that saying goodbye is particularly painful.”
Among the lots is a late 16th century Rheinish carving showing Herod and Salome (estimated at £5000-7000) that Wonnacott said was once in the renowned Welby Collection. He added: “I remain in awe of the quality of the carved detail.”
Another lot, a Birmingham 1905 silver and nephrite heart shaped box containing a bean from the Caribbean, is estimated for sale at £300-500. Wonnacott explained that the bean was “swept by the Gulf Stream and deposited on a romantic Scottish beach, so beloved by the discoverer, that he (or she) had a silver box made and engraved to record the event”.
A solid silver diamond scoop in the form of a dustpan, bought in 1987 from silversmiths Heath & Middleton, carries an estimate of £150-200. Wonnacott said: “To have so many loose diamonds lying around that you needed such a utensil is in itself intriguing.”