Special relationship with relish as First Ladies host barbecue

The two leaders gamely served the cooked meat at the unusual lunch party while their wives, Samantha and Michelle, spooned side dishes on to guests' plates.

About 150 American and British servicemen and women sat at wooden tables in the sunny garden behind Number 10 yesterday, the air around them filled with a mouth-watering barbecue aroma.

The Prime Minister and the President appeared at ease as they performed their catering duties in shirt sleeves, chatting and laughing while they worked.

Mr Cameron appeared to be especially enjoying his role, casually asking the wife of a US marine: "Would you like a burger?"

The two First Ladies also smiled and chatted as they played hostesses, Mrs Cameron dressed in a pale summer dress and green belt and Mrs Obama in a brown patterned jumper and skirt.

Even the menu appeared to reflect the strong transatlantic bond the two countries have insisted upon so firmly, featuring both British and US dishes.

British sausages, Kentish rosemary lamb chops and hot Jersey Royal potatoes were served with American staples such as hamburgers, corn on the cob and coleslaw.

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There was also a tomato, mozzarella and basil salad and Caesar salad, followed by a dessert of summer berries and vanilla ice-cream.

The bilateral partnership was further symbolised by the interspersed Union flag and Stars and Stripes bunting draped overhead.

Both leaders worked together to pile food on to one wounded soldier's plate, as other guests queued for their meal at the food-laden tables.

The atmosphere was a mixture of genteel English garden party and sombre military occasion, with the guests perhaps somewhat overawed by their VIP hosts.

A group of British and American media observed the do from a terrace above the garden but were kept at a safe distance from the barbecue and guests.

The two leaders emerged from Number 10 at 12:30pm, smiling and waving to the massed press photographers outside before both climbed into the back of the presidential vehicle and drove off to the frenzied sound of clicking cameras.

After the barbecue lunch, Mrs Obama travelled to Oxford to speak to a group of schoolchildren.

The First Lady received a rapturous round of applause as she arrived at Oxford University's Christ Church College.

Mrs Obama greeted pupils from Elizabeth Garrett Anderson (EGA) secondary school as she entered the college's dining room, telling them she was "thrilled to be back".

She first met pupils from the north London secondary school two years ago when she paid them a surprise visit during a trip to the capital with her husband.

In a nod to Harry Potter - the dining room was used as the set for the Grand Hall at Hogwarts in the films - the school girls sat at two long tables to listen to Mrs Obama's remarks.

She told the youngsters: "How are you doing? It's good to see you again."

The 37 girls were specially picked for the event because they are interested in science and are not reaching their full potential.

The meeting with Mrs Obama marked the culmination of a day of activities at the university for the youngsters, including campus tours, career discussions and mentoring sessions.

The trip, which was arranged at Mrs Obama's suggestion, has been designed to teach the girls about university and encourage them to think about studying for a degree.

Since visiting EGA in 2009, Mrs Obama has kept in touch with the school, writing letters and encouraging the girls in their studies.

Mrs Obama told the schoolgirls she worried about applying to top universities when she was young because of her background.

She said: "I remember back at a young age trying to decide what schools to apply to and how well-meaning but misguided people questioned whether someone with my background could succeed at an elite university.

"When I was accepted I had all kinds of worries and doubts.

"I wouldn't be as well prepared as students from privileged families and I wouldn't fit in.

"But after a few months away from home I realised I was just as capable and I had just as much to offer (as] any of my classmates."

In an inspiring speech, Mrs Obama, who wore a white jacket with a sparkling belt and black trousers, said: "We passionately believe that you have the talent within you, you have the drive, the experience to succeed at Oxford and universities just like it across the country and the world."

She told the youngsters that they had overcome challenges and hardships in their lives and, from these experiences, they had learned strength, courage and maturity.

Referring to her own experience of attending university, she said: "I realised if I worked hard enough, I could do just as well as anyone."

Success is not determined by background but confidence and effort, she said, telling the girls: "You have to work hard, you have to push yourself."