Newspaper headlines: Universal Credit 'rethink' and train murder

The victim of Friday's fatal stabbing on a train in Surrey, Lee Pomeroy, is pictured on many of the front pages.

Several newspapers lead on tributes from the family of the 51-year-old. The headline in the Sunday Mirror reads: "Our devoted family man".

The Sun on Sunday has spoken to a witness who says he tried to help resuscitate Mr Pomeroy as he lay dying on the platform at Horsley station.

The man - who is not named - describes seeing Mr Pomeroy's teenage son in shock, on the phone to the ambulance service.

Neighbours tell the Mail on Sunday they can scarcely comprehend the family's trauma.

Meanwhile, many of the papers focus on manoeuvrings in Westminster, ahead of next week's planned Commons vote on Theresa May's Brexit deal.

The Sunday Telegraph says the prime minister is "poised to play for time", as her aides draw up a plan to make MPs' approval of the deal conditional on the EU providing further concessions.

Brexiteers tell the Sun on Sunday they fear Mrs May will delay the vote for a second time next week.

One senior MP says she is "time-wasting in the dying minutes" - a metaphor which the newspaper illustrates with a mocked-up picture of the PM as a footballer, shielding the ball next to a corner flag.

In the Sunday Express the prominent Brexit supporter Jacob Rees-Mogg warns that MPs who oppose Mrs May's deal "haven't gone soft over Christmas", with more than 100 set to vote against her.

Meanwhile, the Sunday Times reports that a cross-party group of senior MPs is planning what the paper calls a "Donald Trump-style shutdown" to prevent the UK from leaving the European Union without a deal.

The group of select committee leaders have tabled an amendment to the Finance Bill which - if approved by MPs this week - would strip the Treasury of its power to spend money on a no-deal Brexit.

Members of Mrs May's team tell the Times the plan could paralyse the top of government.

The Observer suggests Labour is facing a "mass exodus" over its Brexit policy - with thousands of party members demanding that it opposes the PM's Brexit deal, and backs a second referendum.

The newspaper says at Labour's national policy forum this week, officials will offer testimony that local activists are quitting the party over the issue.

Writing in the paper, the columnist Andrew Rawnsley believes the split comes down to a fundamental disconnect between Labour's grassroots and the outlook of party leader Jeremy Corbyn.

He says Mr Corbyn does not hate Brexit and does not want it reversed - and if party members want another vote they will have to revolt.

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The Sunday Telegraph reports that Russia is trying to set up a new network of spies in Britain in the wake of the Salisbury attack.

Government sources tell the paper the Kremlin has ordered its foreign intelligence service, the SVR - the equivalent of Britain's MI6 - to gain a foothold in the UK.

Security officials are reportedly concerned, because they believe the SVR is a "more effective and dangerous organisation" than the military intelligence service, the GRU, which was blamed for the Salisbury poisonings.

Meanwhile, with the headline "ultimate betrayal", the Mail on Sunday reports that a woman has been ordered to pay her ex-husband £250,000, after he claimed to have found out that his three sons were not biologically his.

The man apparently made the discovery two years ago, after being diagnosed with cystic fibrosis, which causes infertility from birth in men.

He tells the Mail he feels like he has been "living in the Matrix" - not knowing what is real, and what is not.

The Sunday Times leads on NHS data showing that more than 40,000 obese people needed hip or knee surgery last year - including seven teenage girls.

The paper says it marks an increase of 575% compared to eight years ago, with the cost reaching £200m annually.

Campaigners describe the figures as "horrifying" and complain to the Times that all governments have not taken the issue seriously.

Elsewhere, the Sunday Times quotes unhappy Marks and Spencer customers who bought meals from its new vegan-friendly "Plant Kitchen" range only to discover allergy warnings for egg and dairy on the packaging.

One lactose-intolerant shopper says she had assumed that, being a product for vegans, her dish would be safe to eat.

The Observer also examines the growing range of vegan products in supermarkets, saying some stores have now crossed what it calls the "final food frontier" - vegan fish.

It says customers will soon be able to buy vegan prawns, vegan smoked salmon - and what has been termed "fish-free" tuna.

And a Scots Guardsman has told the Mail on Sunday that he plans to resign from the Army, because his face was pictured beneath the word "snowflakes" in a recruitment poster.

He claims not to have been forewarned, and that colleagues have since been bombarding him with mocking messages.

The paper says the Guardsman first voiced his fury in a Facebook discussion with other soldiers, where many expressed disdain about the £1.5m recruitment drive.