Singer Annie Lennox and Hollywood star Reece Witherspoon were in Westminster this week to promote causes close to their heart.
Lennox, who shot to fame as the vocalist in Eurythmics and has gone on to have a successful solo career, made an impassioned plea for better treatment for people living with HIV.
She spoke at the launch of a new report into HIV stigma in the UK.
"This initiative will become a significant tool to inform not only those who are personally or professionally involved with the challenges of HIV, but it will hopefully also help to influence change," she said.
"Stigma and discrimination still remain prevalent, and continue to be a massive obstacle; this will be a hugely significant first step."
She urged people to work in a coalition, led by people living with HIV but including experts such as doctors, to improve society's attitudes.
Lennox said women in particular need to work together to fight stigma.
The Scottish vocalist said that HIV is not "on the radar in the UK" and that 'complacent' attitudes are reflected in the level of misunderstanding there is about the disease.
She described stigma as "the new HIV epidemic".
Lennox was joined at the launch event by experts, researchers and people living with HIV from across the country.
David Borrow MP, chair of the all-party parliamentary group on AIDS, said:
"The fact that treatment exists means the number of people living with HIV will continue to grow."
The report revealed that 46 per cent of those questioned were not sure their medical records are being kept confidential; 63 per cent were aware of being gossiped about in the past year and of the 88 per cent who knew of support available for them, only 28 per cent had sought support.
"Developing nations are ahead of us in dealing with stigma," Borrow said.
He added that people living with HIV have the right to be treated the same as if they had any other long-term illness.
Lennox told ePolitix.com that she has been to Westminster before to campaign on behalf of people living with HIV.
For Reese Witherspoon it was her first visit to the palace.
The Legally Blonde star was here to launch a joint campaign by cosmetics manufacturer Avon and the charity Refuge to get more government funding for victim support services in the UK.
Witherspoon said one of her friends suffered from domestic abuse.
"She was a young woman and felt intimidated and ashamed and I was lucky enough to be in a situation where she confided in me," she said.
"I cannot tell you a person that I've met on Earth who hasn't had this experience.
"I've seen so many people who have suffered in silence and who are embarrassed or ashamed."

Dods Parliamentary Communications Ltd