Ms Harman is amongst ministers running the country while Mr Brown holidays
Labour's deputy leader Harriet Harman has denied her high profile comments this week are part of a bid to position herself to be a future party leader.
But Ms Harman told BBC Radio 4's Woman's Hour she would not "tippy-toe" around issues she believed in and would not become a "shrinking violet".
She denied cabinet splits over rape laws or "grandstanding" as stand-in PM.
Ms Harman played down differences with Lord Mandelson despite saying they occupied "different eco-systems".
There had been reports the two of them were divided over the issue of increasing parental leave rights and flexible working rules - with Lord Mandelson blocking moves for fear of hurting firms already hit by the recession.
Ms Harman said both she and Lord Mandelson - "a big and important figure who I strongly support in government" - wanted firms to survive the recession and prosper.
She said supporting families would help boost the economy in the years to come so they were not in competition: "We are in different eco-systems if you like, him in the world of business and me putting arguments for families, but they are both complementary."
Ms Harman, who is Leader of the House of Commons as well as Labour's deputy leader, is standing in for Gordon Brown for the first bit of his holiday and has used her time in charge at Downing Street to highlight her concerns about equality.
She has appeared to suggest men were to blame for the credit crunch and told a newspaper one of Labour's top two posts should always be held by a woman and said men "cannot be left to run things on their own".
Asked about these comments and the largely critical newspaper reaction to them, she said, "I'm not going to become a shrinking violet" and said "there's no point tippy-toeing around".
The women's and equality minister also insisted the timing of her comments was "absolutely not" a bid for the Labour leadership.
Some newspapers have reported that some Cabinet ministers have been annoyed by Harriet Harman's comments this week.
The former Deputy Prime Minister, John Prescott, criticised her in public after she suggested Labour should never again have a men-only leadership team. Mr Prescott said she should "stop complaining and get campaigning".
Ms Harman said she rejected Mr Prescott's attack because as deputy leader and a cabinet member she was not complaining about things - "I don't have anyone to complain to apart from myself" - but was getting things done.
She said when she had first got into Parliament there were very few women MPs and she was warned not to "keep going on about women - but if I wasn't going to do so who was going to?"
Ms Harman said in the past her comments, such as on prostitution laws, had been controversial at the time but subsequently became "conventional wisdom".
She told the programme she would not abandon her "responsibility" to continue to push the case for "fairness, social justice and women".
Ms Harman said there should be a woman in the top team to ensure that issues "which affect women in this country are addressed as matters of importance".
Asked about her future, Ms Harman told Woman's Hour she was "proud to be Gordon Brown's deputy" and would work with colleagues in Government to get the country through "a very difficult time on the economy".
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