Founder Michelle Mone is believed to be on the lookout for a new beauty after a series of disagreements between racks on the contract of Kelly.
Friends say that Michelle was not happy when Kelly signed up to a session of nude for Playboy magazine for £ 345,000 which has been a breach of his contract Ultimo.
The lingerie line has a star on the faces of the previous.
PHOTOS: Curvy Kelly in Smalls
Rod Stewart's girlfriend Penny Lancaster was the first celebrity, followed by his ex Rachel Hunter. Others include Lisa Snowdon, Helena Christensen and Sarah Harding.
Ex-Spice Girl Mel B was the girl before Ultimo Kelly. Past models have pocketed up to £ 1 million for their contracts.
Kelly, 30 - whose perfect figure hourglass comes in at 34E-26-36 - is dating rugby ace Danny Cipriani, 22. She also starred in Strictly Come Dancing and appears in the new horror film Piranha 3D, in the month of August.
