Boris Johnson is mourning the loss of his mother after she died aged 79.

Charlotte Johnson Wahl, a painter, died “suddenly and peacefully” at St Mary’s Hospital, Paddington, on Monday according to a death notice in The Times.

Mr Johnson once described his mother as the “supreme authority” in the family and credited her with instilling in him the equal value of every human life.

The notice in the Times says she was a “Painter. Mother of Alexander, Rachel, Leo, and Joseph; grandmother of Ludovic, Lara, Charlotte, Milo, Oliver, Cassia, Theodore, Rose, Lula, William, Ruby Noor, Stephanie and Wilfred.”

Labour leader Sir Keir Starmer was among the first politicians to offer his condolences.

“I’m very sorry to learn of the Prime Minister’s loss. My condolences to him and his family,” he tweeted.

Tory MP Conor Burns said: “So sad to hear of the death of Boris Johnson’s Mum. Thoughts and prayers are with him and the whole of the Johnson clan.”

Fellow Conservative Angela Richardson added: “Sad news for the PM tonight as well as the rest of the Johnson family. Thoughts with them all.”

Conservative Party co-chairman Amanda Milling tweeted: “Thinking of Boris Johnson and his family this evening. Our thoughts and prayers are with you.”

The daughter of the barrister Sir James Fawcett, who was president of the European Commission for Human Rights in the 1970s, Mrs Johnson Wahl studied English at Oxford University.

She interrupted her education to travel to America with Stanley Johnson – who she married in 1963 – before returning to complete her degree as the first married female undergraduate at her college, Lady Margaret Hall.

The couple had four children – Boris, journalist Rachel, former minister Jo and environmentalist Leo – before they divorced in 1979.

As an artist, she made her name as a portrait painter – her sitters included Joanna Lumley and Jilly Cooper – although throughout her life she painted other subjects, including landscapes.

In the years following her divorce, she refused to accept any money from her former husband, eking out a living by selling paintings. She later recalled she was “very hard up”.

In 1988, she married the American professor Nicholas Wahl and moved to New York where she began painting cityscapes – which were the subject of a sell-out exhibition in 2004 – but returned to London following his death in 1996.

At the age of 40, she was diagnosed with Parkinson’s disease but she never allowed her illness to prevent her painting, steadying herself with a walking frame as she worked.

Paying tribute to her charity work, chief executive officer at Parkinson’s UK said they could “never thank her enough”.

Caroline Rassell said: “Today is, of course, a very sad day for Charlotte’s family, but also for the wider Parkinson’s community.

“As well as being a valued member of our Kensington and Chelsea Support Group, Charlotte was also an active campaigner. She happily and generously used her voice and influence to back our campaigns, whilst also raising awareness of the condition by speaking about her experience. She also supported us by hosting an exhibition at the Institute of Contemporary Arts, using her wonderful artistic eye to fundraise.

“These little actions made a real change to the lives of the 145,000 people in the UK living with Parkinson’s and their loved ones. For that, we could never thank her enough.

“Our thoughts are with her family and friends.”

In 2015, she was the subject of a retrospective exhibition at the Mall Galleries in London.