UAE leaders sent messages of condolence to UK Prime Minister Boris Johnson on the death of his mother.
President Sheikh Khalifa sent his condolences to Mr Johnson on Tuesday after Charlotte Johnson Wahl's death.
Sheikh Mohammed bin Rashid, Vice President, Prime Minister and Ruler of Dubai, also sent his sympathies to Mr Johnson, state news agency Wam reported.
Sheikh Mohamed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the Armed Forces, sent a similar message of support.
Wahl died at St Mary’s Hospital in Paddington, London, on Monday “suddenly and peacefully” at the age of 79, according to a death notice in The Times.
Tributes to her were paid by MPs across the political spectrum.
Labour leader Sir Keir Starmer wrote on Twitter that he was “very sorry to hear of the Prime Minister’s loss”.
The mother of four received a diagnosis of Parkinson’s disease when she was 40 years old.
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.
A professional painter, Wahl has been remembered by her curator Nell Butler as an “astonishing self-taught artist” who had an “indomitable spirit”. Referring to Wahl as a “huge talent,” Ms Butler said the artist had continued painting “almost until the end”.
“She was driven to put things on paper. It was a language for her, a way of communicating the emotions and colour inside her head,” said the curator of Wahl’s retrospective collection, Minding Too Much, held in 2015, at the Mall Galleries in London.
“She had an indomitable spirit and never complained, despite the burden of Parkinson’s and the indignities of old age."
Ms Butler described her paintings, which included scenes from 9/11 and the King’s Cross fire and some of which were produced during periods of mental illness, as “intensely powerful and raw”.
Wahl was a campaigner of the Kensington and Chelsea Support Group for Parkinson's UK.
The charity’s chief executive, Caroline Rassell, said the late artist’s work “made a real change to the lives of the 145,000 people in the UK living with Parkinson's and their loved ones” and “for that we could never thank her enough”.
The daughter of the barrister James Fawcett, who was president of the European Commission for Human Rights in the 1970s, Wahl married Stanley Johnson in 1963.
The couple had four children, Boris, journalist Rachel, former politician Jo and environmentalist Leo, before they divorced in 1979.
As an artist, she made her name as a portrait painter. Her sitters included actress Joanna Lumley and novelist Jilly Cooper, although throughout her life she painted other subjects, including landscapes.
In the years following her divorce, she refused to accept money from her former husband, eking out a living by selling paintings, before marrying American academic Nicholas Wahl in 1988 and moving to New York.
She returned to London after his death in 1996.