Newspaper headlines: Starmer 'attacks Trump' and 'No way back for Harry'

Activists from environmentalist group Just Stop Oil are planning to occupy MPs' homes ahead of the general election, according to the Mail on Sunday

The death of the Kremlin critic, Alexei Navalny, continues to make Sunday's headlines.

The Sunday Times says Russian intelligence officers are reported to have visited his prison two days before he died there. Human rights campaigners claim the FSB disconnected and dismantled security cameras and listening devices.

The Sunday Telegraph suggests Mr Navalny's wife, Yulia Navalnaya, could step into her husband's shoes as the Kremlin's chief foe. The paper says her "years of strength and unwavering commitment to the cause of freedom in Russia" mean she is ready.

"Don't let Navalny's death be in vain", is the message from the editorial in the Sun on Sunday. The paper says what happened to him "must unite the West like never before against Vladimir Putin's murderous tyranny".

The Observer is equally emphatic. "Putin must be shown he can't kill with impunity," reads the headline of its editorial. The paper calls for the West to break off diplomatic relations with Moscow. "Expel its lying, scheming diplomats" it says, and "send them all packing".

The Sunday Telegraph leads on what it calls a "broadside" from the Labour leader, Sir Keir Starmer, towards Donald Trump after the US presidential hopeful's criticisms of Nato. Mr Trump has said the United States will "not protect" alliance members that fail to meet defence spending targets. According to the Telegraph, Sir Keir has insisted that, if he is elected Prime Minister, Britain will always stand up for its allies "even if others threaten not to".

The Sunday Mirror reports that the government might call the general election in May. One former Conservative minister is quoted as saying a poll then would avoid challenges to Rishi Sunak's leadership and a damaging race to replace him.

The Sunday Times, though, says the election is still expected in October or November. The paper also reports there are predictions that up to 150 Tories could announce they are quitting as MPs if polls continue to suggest Labour is on course for a landslide.

The Mail on Sunday says it's discovered that activists from environmentalist group Just Stop Oil are planning a "sinister nationwide blitz" to occupy MPs' homes ahead of the general election. The paper says protestors told its undercover reporter they were ready to look a "bit loony" to get attention for their cause. A Just Stop Oil spokesman is quoted accusing paper of getting "in a tizz" about "ordinary people taking the power back".

And finally, the Observer says the mainstay of casual conversation, the unexpected state of the weather, is under existential threat. The paper reports that scientists are beginning research to determine weather patterns a month into the future. While one of the experts from Reading University has stressed it will not be possible to predict if a particular day will be rainy or sunny, the researchers hope to be able to say if we are likely to experience a very wet or windy period four weeks in advance.

Sign up for our morning newsletter and get BBC News in your inbox.