The government was on Thursday evening urgently trying to regain control of the next phase of the pandemic crisis as it faced fierce criticism and warnings that mixed messaging was priming the public to give up on the lockdown. Downing Street’s plans for laying out a “roadmap” on Sunday were thrown into chaos by a rash of headlines pointing to a significant easing next week. This prompted concern from many quarters, including from one of the government’s scientific advisers who said the public were mistakenly being given a “green light” to abandon the lockdown. “It’s really unhelpful to have bits and pieces of information leaked,” a member of the Sage advisory committee told the Guardian. “It’s incredibly damaging. If people are primed to look at things in a certain way, it will shape how they receive the information. So on Sunday they will be looking for the green lights and they won’t notice the red lights. It’s a really powerful way of influencing people.” The mixed messages emanating from the government also infuriated the Scottish and Welsh governments, threatening to rupture the “four nations” approach No 10 has sought to pursue. As ministers scrambled to dampen expectations before the bank holiday weekend, Dominic Raab insisted any changes to the lockdown made by the prime minister on Sunday will be “modest, small, incremental and carefully monitored”, after a chorus of voices warned against relaxing restrictions prematurely. Sunbathing, long walks and “unlimited exercise” are likely to be permitted, government sources suggested. But Downing Street poured cold water on the idea of wider changes, saying Boris Johnson had told his cabinet he would exercise “maximum caution” in moving to the next phase of the crisis. And Raab said: “As we enter another long bank holiday weekend I think the message is very clear: follow the guidance. There is no change today in the guidance or in the rules, but the prime minister will set out a roadmap on Sunday.” Johnson briefed opposition leaders about plans for the next stage on Thursday, and one source with knowledge of the call said he appeared “almost uncomfortable” about some of Thursday’s front pages, whose headlines included Happy Monday and Hurrah! Lockdown Freedom Beckons. “This was not bombastic Boris, he was quite a different character. He was far more doveish about lockdown than has been suggested,” the source said. The Scottish first minister, Nicola Sturgeon, warned that it would be a “potentially catastrophic mistake” to move too quickly. And a statement from the Welsh government said: “Some of the reporting in today’s newspapers is confusing and risks sending mixed messages to people across the UK.” The Welsh education minister, Kirsty Williams, later insisted the country’s schools would not open on 1 June, whatever England decides. And she urged the Welsh public not to share information from “other sources”. Baroness Sal Brinton, a former president of the Liberal Democrats who has been leading the party’s response to the coronavirus outbreak, said: “I think people are taking it to mean they can travel around for the bank holiday weekend. I’ve already seen more tweets about lots more traffic on the roads. “They are mishandling the announcement in order to be seen to speak to people who are frustrated. I want an end to the lockdown but I want it to be done when people are safe and the government need to come and explain it to parliament.” Teaching union NASUWT urged the education secretary, Gavin Williamson, not to reopen English schools fully until September, amid widespread expectations of a phased return for the children of non-key workers from 1 June. In a letter to Williamson, Patrick Roach, the general secretary of the NASUWT, said: “In view of the continued and pressing public health challenges and the considerable task that will be required to ensure that every school is ready to admit increased numbers of children and adults into safe learning and working environments, the NASUWT urges the government to end speculation on the reopening of schools beyond the current restrictions prior to September 2020.” The Labour leader, Keir Starmer, emphasised the importance of a cross-UK consensus on leaving lockdown and called on Boris Johnson to involve the devolved nations and opposition parties in “meaningful” discussion. “Having different approaches and rival strategies isn’t going to help. I’m not talking about [more cautious nations having] a veto but my strong preference is that the whole of the UK move as one on this,” he said. Speaking to Scottish lobby reporters, he added: “It is really important in Scotland and across the UK that we are cautious about this, that nothing is done that might push the infection rate above one. There is a strong preference on my part that this is done across the UK as a whole. That’s the approach we took going into lockdown, that’s the approach we should be taking coming out.” Meanwhile, police chiefs warned the lockdown is slowly ebbing away and some said further loosening would make some aspects “unpoliceable”. The warnings comes ahead of a long bank holiday weekend to mark VE day, with the forecast warm weather likely to tempt people to go out after six weeks of restrictions. Several police chiefs told the Guardian that more people were going out by foot and road and there were clear signs of people getting tired of lockdown. At least one force said it was scaling back part of its enforcement for fear of losing public support. Senior government figures were irked by some of Thursday’s newspaper front pages, with one source saying they had “over-egged” both the “tone and the pace” of likely changes. Thursday’s daily press conference was told R – the infection rate for the virus – may actually have risen, because of the scale of the epidemic in care homes. The government has said R is crucial to determining when restrictions can be lifted. Care homes operators said lifting the lockdown would be “reckless” and only increase infections in their facilities, which have seen the virus claim 6,686 lives up to 1 May in England and Wales amid ongoing shortages of personal protective equipment and testing. Sam Monaghan, chief executive of MHA, the UK’s largest charitable provider of care homes, which operates 222 schemes, said: “Given the perilous state the social care sector continues to find itself in, easing restrictions, which will no doubt lead to greater spread of Covid-19 in the general population, will inevitably increase the risk of infection to our staff and our homes ... without a comprehensive plan for the care sector, easing restrictions would be a reckless move. “We know that in those countries where they have been able to control the spread of the virus in care settings, it is because they have up and running effective contact-tracing and testing and this has decreased the spread of the virus in the general population.” The prime minister told MPs on Wednesday there had been a “palpable improvement” in the situation in care homes in recent days. With the lockdown extending into a seventh week, the influential Conservative thinktank Onward is warning the government about the impact on the nation’s mental health. “As the Covid-19 crisis progresses, we are likely to face increased levels of depression, harmful use of alcohol and drugs, as well as self-harm or suicidal behaviour,” it says, in a report called Building a Social Stimulus published on Friday. “In the longer term there is likely to be an increase in cases of post-traumatic stress disorder, both amongst healthcare workers and those who have suffered grief or serious illness.” The thinktank calls for a £5m boost to mental health support charities. And it urges the government to reopen parks first, prioritise reestablishing family contacts and ensure the carers of vulnerable people can be tested for the virus.