Janet Morrison has stepped down as chief executive of the older people’s charity Independent Age after nearly 12 years in the role.
A spokeswoman for Independent Age, which offers support and advice to older people, said Morrison had left the charity with immediate effect.
She had been chief executive since March 2007, having previously been deputy chief executive of the innovation charity Nesta.
In a statement, Morrison said: "After 12 years working at Independent Age I have come to the decision that it’s time for me to leave a job that has taught me so much over the years.
"With the arrival of a new chair later this year, and the start of a new five-year strategy for Independent Age, it’s time to hand over the reins to a new chief executive to create the roadmap for the years ahead."
She said she would continue to be a passionate supporter of the charity’s work and of the Campaign to End Loneliness, for which she was the founding chair.
"Everything that I have achieved has been through my committed and creative colleagues, past and present," she said.
"I know Independent Age and the Campaign to End Loneliness will continue to go from strength to strength."
A spokeswoman for the charity was unable to confirm whether Morrison would be moving into another paid role immediately.
The charity would recruit an interim chief executive while a permanent successor to Morrison was sought, the spokeswoman said.
Justine Frain, chair of Independent Age, said: "Janet has overseen a transformation of the charity during her period in charge, increasing the reach and range of services provided to older people.
"She is a passionate advocate for older people and was instrumental in founding the Campaign to End Loneliness.
"We are grateful to Janet for all she has achieved during her tenure and wish her all the best in her future endeavours."