Sarah's heroes: The PM's wife has been making friends in surprising places.

Together they have trudged through mud at Glastonbury and dined at countless functions in aid of maternal health. But Sarah Brown has now sealed her unlikely friendship with Naomi Campbell by nominating the supermodel as her 21st-century heroine.

The Prime Minister's wife makes the surprising endorsement in next month's issue of Harper's Bazaar, because of Campbell's charity work.

Campbell is a global ambassador for the White Ribbon Alliance, of which Mrs Brown is a patron and which campaigns to make pregnancy and childbirth safer for women in developing countries. Mrs Brown says: "The Naomi Campbell I had heard about was beautiful, successful, a bit frightening, even a bit out of control. The Naomi Campbell I met was certainly beautiful, but also sincere, direct and impatient in a good way." Mrs Brown's friendship with the Streatham-born model is the most prominent in a string of celebrity alliances the PM's wife has created. On Friday evening, Mrs Brown hosted a party at Downing Street for fellow Twitterers – dubbed "downingtweet" – where guests were treated to a performance by the singer Beverley Knight.

In April this year Mrs Brown dined at the same table as Campbell and Paris Hilton at a function in aid of the African First Ladies Health Summit in Hollywood. After the event she posted on Twitter: "Loved Paris Hilton who I met last week in LA for the first time."

The January issue of Harper's Bazaar is on sale on 7 December

...and Gordon's heroes

But the PM himself prefers saviours to celebs, says Jane Merrick

On the eve of becoming Prime Minister in 2007, Gordon Brown declared that Britain was moving on from an age when "celebrity mattered". Attempting to draw a line in the minor-celebrity-obsessed sand, he said: "What I don't agree with is that the public is in love with trivia." So it is little surprise that his heroes, who took centre stage in his book on the subject, are a little different from his wife's. In his book Courage, Mr Brown praised Martin Luther King, Nelson Mandela, Robert Kennedy and Aung San Suu Kyi.

He also paid tribute to Dietrich Bonhoeffer, who took part in the German resistance against the Nazis; Cicely Saunders, the mother of the hospice movement; Edith Cavell, the British nurse who was executed for helping soldiers flee Belgium during the First World War; and Raoul Wallenberg, the Swedish humanitarian who rescued Jews during the Second World War. At the Labour conference in 2006, Mr Brown claimed to be "more interested in the future of the Arctic Circle than the future of the Arctic Monkeys". However, last year he invited George Clooney to No 10 and spoke by phone to the Latin singer Shakira to launch a campaign for universal education.

Only last week, Mr Brown name-checked the actress Reese Witherspoon, who was speaking at an event for domestic violence victims. It was perhaps reassuring that Mr Brown conflated her with Renée Zellweger when he said: "I am very grateful that Renée Witherspoon is leading this campaign."