It has been claimed that Smith's television series Delia's How to Cook led to a 10% rise in egg sales in Britain and her use of ingredients such as frozen mash and tinned minced beef and onions, or utensils such as an omelette pan, could cause sell-outs overnight. This phenomenon, dubbed the "Delia effect", was most recently seen in 2008, after her book How to Cheat at Cooking was published. Her fame has meant that her first name has become sufficient to identify her to the public and the "Delia effect" has become a commonly used phrase to describe a run on a previously poor-selling product as a result of a high-profile recommendation.
In 2008, it was reported that Smith had rejected an offer from Norfolk-born billionaire Peter Cullum, who wished to invest £20 million in the club, but wanted Smith and the other shareholders to relinquish their holdings. Both Smith and Cullin denied this offer had been made, with Smith telling the football club's AGM that she and her husband would be "very happy to stand aside" as majority shareholders if someone came along with an offer to buy them out.