You see her here, you see her there. Sarah Brown, the normally reticent wife of the Prime Minister, is coming out into the open to battle for her husband's political career.

She is the cook behind the "lasagne offensive", which Gordon Brown has launched to improve working relationships with his cabinet ministers. She has also stepped up the frequency of her public appearances, displaying the easy social skills she honed as the founder a PR agency before her marriage – skills in which her workaholic husband is notoriously deficient.

It is barely a month since two cabinet ministers, James Purnell and Hazel Blears, walked out of the Cabinet complaining, in effect, that they could not work with Brown any more. He is accused of operating through a tiny cabal, which includes his old ally Ed Balls and the Cabinet First Secretary, Peter Mandelson, keeping other ministers out of the loop. Caroline Flint, a middle-ranking minister who attended Cabinet, complained she was there only as "window dressing" when she too resigned.

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Now, sitting at a round table with the smell of Mrs Brown's cooking in their nostrils, ministers can have a more relaxed conversation with the Prime Minister than they can ever have in the cold formality of the Cabinet room with civil servants taking notes.

It is hoped that in these friendly chats Mr Brown can persuade his cabinet colleagues not to get involved in plots to remove him, which some fear will break out again in the autumn.

"He has been seeing a number of cabinet ministers socially, in the way you would expect in the run-up to the long summer break," Mr Brown's spokesman confirmed yesterday. "But we are not going to be running a commentary on the menu – whether it is lasagne, pasta, or takeaway pizzas."

There has only been one hiccup so far. Mr Brown's aides are still simmering because the Home Secretary Alan Johnson, a guest at one of the lasagne dinners, did not mention that he was going to make a public statement the next day that ID cards will never be compulsory, which changed the policy laid down by the Prime Minister.

Mrs Brown, 44, has also been appearing in public as an informal ambassador for Downing Street and will be visible again when world leaders meet at L'Aquila in Italy for the G8 summit on Wednesday.

While her husband argues for more action to stimulate the world economy, she will carry out her separate programme of engagements, promoting charities with which she is associated.

Mrs Brown was photographed at the weekend marching alongside Michael Cashman, the openly gay Labour MEP at the gay pride march in London. Mr Cashman and Mrs Brown were flanked by two men in drag.

She has also given a huge boost to the campaign run by Janis Sharp, the mother of a computer hacker who is the centre of an extradition battle. Mrs Sharp's son, Gary McKinnon, who has Asperger's syndrome and is obsessed with UFOs, went computer hacking to hunt for "little green men". American security officers were not amused. In the US, Mr McKinnon is accused of being a "cyber terrorist", and if extradited could face a 60-year jail sentence.

Mrs Sharp had nothing but praise for the Prime Minister's wife after they met in Downing Street. "She filled up with tears and I filled up with tears," she said. "She was very moved and was incredibly sympathetic. She is a lovely, genuine person who clearly cares about people. I think it was incredibly brave of her to meet us. It was very heartening."

And for her next trick... Mrs Brown to edit magazine

*Sarah Brown's next project will showcase her PR skills, when she guest-edits an edition of Fabulous magazine, a News of the World supplement. The Prime Minister's wife, patron of the health research charity Wellbeing of Women (WoW), has been working with the Fabulous editorial team to produce a special edition on women's health issues. It includes her interviewing Jools Oliver, wife of the TV chef Jamie, who overcame fertility problems to give birth to three healthy children.

"Guest editing this issue has certainly been a brilliant new experience for me," Mrs Brown said in a statement. "I've loved every minute. The 19 July edition marks the start of a campaign by the magazine to raise funds to help WoW's scientists make the next breakthroughs in women's health. They do groundbreaking work. It's vital to share information with as many women as possible across Britain."