Former public schoolboy Simon Ambrose was the surprise winner of The Apprentice last night, beating single mother and the television show's favourite, Kristina Grimes.

The result is a remarkable victory for Mr Ambrose (27), who programmed one of Sir Alan Sugar's Amstrad computers at the age of six after being given it as a present by his father.

Unlike the two previous winners of the BBC programme - Tim Campbell and Michelle Dewberry - Mr Ambrose comes from a well-off background.

Ms Grimes (36), who put herself through university after having a baby when she was 17, was upset after learning of the choice. Her ruthless streak, strength as a team leader and organisational skills had made her a favourite to win the third series of the show.

While Sir Alan's colleague Margaret Mountford sung Ms Grimes's praises, fellow adviser Nick Hewer believed Mr Ambrose "can see over the horizon". In the final task, Mr Ambrose won over architects and property experts with his design for a new building in London's South Bank.

Just before the decision, Mr Ambrose told Sir Alan he would "work my cotton socks off for you". Sir Alan then said: "It's a very difficult decision. There's only one job. I've got someone who's very experienced. I've also got someone who's enthusiastic, a great talker and willing to learn. But I'm thinking to myself 'do you want to be the headmaster again?'. Simon, you are not a good leader of people, that's something you need to work on. Yet you suddenly surprised me with very good innovative ideas and a well thought-out presentation. Kristina, you are a thinker, you don't rush into anything. You're a great saleswoman. You brought your child up in difficult circumstances and now it's Kristina time. Simon, some devil inside me says I wouldn't like to let you go either." He then told Mr Ambrose: "Bloody old fool that I am, I'm going to take that risk, you're hired."

Holding back tears, Ms Grimes said: "I came on this intent on getting the job with Sir Alan. My heart and soul was in this, so it's very tough. I was so confident, I really was."

She told her opponent: "As I've said to you before, if you win and screw this up, you won't have Sir Alan coming after you, you will have me." She added: "I wouldn't have done anything differently. I don't necessarily agree with the decision. I'm quite emotional about it." - (PA)