Jemima Khan, the ex-wife of cricketer-turned-politician Imran Khan, joined a protest outside the Pakistani High Commission on Sunday, demanding his release and lifting of the emergency.
"I'm doing this because Imran and my friends in Pakistan have asked us to make noise here because they are not able to in Pakistan," she said addressing the demonstration of about 150 people.
"I think it is time for Musharraf to resign," the 33 year-old said as she handed over a petition to the High Commission. She also called on the British government to continue to put pressure on the General to resign.
"I am doing it because I care about Pakistan and I care about the issue of democracy and human rights," she was quoted as saying by the BBC.
Imran was arrested last week along with thousands of other political opponents of President Pervez Musharraf. Jemima, who helped set up the Free Pakistan Movement with the help of lawyers, journalists, doctors and other professionals, attended the demonstration with the youngest of her two sons.
The eight-year-old boy held a picture of his father with the words "Release Imran. Release my Aba" - which is Urdu for father.
Jemima said her ex-husband's sisters, his female cousins, and an elderly aunt had also been detained after taking part in protests in Pakistan.