By Simon Murphy If he is sweet enough on their pitch, fans see Lord Alan Sugar hand wannabes on The Apprentice a £250,000 investment and tell them: “You’re my business partner.” But as the tycoon’s reality TV hit returns to the BBC next month, our research shows he is still in business with just two of the past 10 champions. They are last year’s winner, boxing gym owner Marnie Swindells, and Dr Leah Totton, who runs cosmetics clinics after taking 2013’s crown. Marnie said they had a “great relationship”, adding: “He has a sharp sense for businesses he believes will do well and the people he wa…