Newspaper headlines: PM's 'secret Brexit deal' and funfair horror

A report of a "secret" Brexit plan and the latest on Arron Banks are among the topics leading Sunday's newspaper front pages.

The Sunday Times thinks the Prime Minister has secured a breakthrough with the EU and that preparations for a final Brexit deal are far more advanced than previously thought.

It says it has pieced this together by speaking to ministers, advisers, civil servants and EU officials.

Under the plans, the whole of the UK would remain within a customs union, avoiding the need for physical checks along the border between Northern Ireland and the Republic.

The EU is also said to have offered a significant concession, by accepting that checks on goods can take place in factories and shops rather than at the Irish border.

And, the paper adds, the plan keeps open the prospect of a free trade deal in a move designed to appeal to Eurosceptics.

Downing Street dismisses the Times' report as "speculation" and says negotiations are ongoing.

In its top story, the Observer alleges the businessman Arron Banks may have misled parliament about links during the EU referendum between his pro-Brexit campaign, Leave.EU, and his insurance business.

The paper says the claim is based on hundreds of internal emails leaked by former employees from Eldon Insurance and Rock Services.

According to the Observer, the emails indicate that his employees worked on some of Leave.EU's most controversial campaigning, including one which highlighted the issue of immigration.

The paper says that Mr Banks has declined to respond to any of the allegations.

In the past he has vehemently denied there was a relationship between the pro-Brexit group and his firms, telling MPs that Leave.EU and his company Eldon Insurance were separate organisations with completely different staff.

Also in the Observer, Britain's only NHS gender identity clinic for children is reviewing its operations because concerns have been raised by a senior member of staff.

The Tavistock Centre is looking at the claim that it is not doing enough to examine the psychological and social reasons behind the desire of some its patients to change gender.

The paper says the review has been backed by some parents of transgender children who are worried that young people are being "fast-tracked" into life-altering decisions.

The centre tells the paper it doesn't limit the time for assessments and these are extended in complex cases.

Transport Secretary Chris Grayling has suggested the second part of the high speed rail line HS2 - connecting Birmingham to Leeds - may never be built, according to the Sunday Telegraph.

The newspaper draws on trade magazine New Civil Engineer's coverage of a rail conference last month.

Mr Grayling told industry figures at the conference they needed to help make the case for HS2 amid questions about its value for money. The government insists the entire line will be complete by 2033.

Meanwhile, the Mail on Sunday leads with a report that Downing Street has made an official complaint about some of BBC Radio 4's coverage of last week's Budget, with one government aide claiming the BBC broadcast its "most biased bulletin in history".

The paper says Number 10 took exception to a news report on the findings of think tank the Resolution Foundation, which concluded the Budget would leave low and middle-income families facing a squeeze.

The government maintains those on the lowest incomes will benefit the most from the chancellor's announcements.

The BBC says it covered the research because it was the first detailed analysis of the Budget, adding it was clearly attributed on-air to the think tank.

Meanwhile, an investigation by the Sunday Times has found that drugs gangs are buying chemicals from China to make new strains of the drug spice, which is blighting British towns.

It says an undercover reporter was offered large Chinese shipments of the chemicals - a practice which is netting gangs huge profits.

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The top story for the Sunday Telegraph reports the government will suggest that companies offer perks such as free fruit, bicycle loans and counselling to keep their workers healthy.

The proposals have been drawn up by Health Secretary Matt Hancock who wants employers to do more to relieve the pressure on the NHS and improve the health of the nation.

Elsewhere, "grief for the boss" is the headline in the Sunday Mirror which carries a picture of Leicester City's entire squad and backroom staff linking arms around the centre circle at the Cardiff City stadium.

Fans wore white t-shirts bearing the image of Vichai Srivaddhanaprabha, who died in a helicopter crash eight days ago.

And several of the papers reveal an unusual holiday habit of Princes William and Harry: litter-picking.

The princes have told a BBC One documentary that their father, Prince Charles, used to get them to pick up rubbish in a bag while strolling in Norfolk and they believed this to be perfectly normal.

According to the Sunday Express, Harry was mocked at school for this habit - but he urges everyone to do it.