On Sunday night, Boris Johnson outlined his "first sketch of a roadmap" for the gradual lifting of coronavirus lockdown measures.
The prime minister said that from Wednesday people would be allowed to drive to the countryside and beaches, as long as they maintain a safe social distance from others.
Tourism chiefs in Cornwall and Cumbria, which includes the popular destination of the Lake District, have reacted with dismay and trepidation to the changes, including the PM's decision to relax his "stay home" slogan to "stay alert".
They have instead urged clarity and caution, asking people not to visit the counties for day trips or staycations until it is safe to do so, for fear of crowds flocking to tourist hotspots and triggering a second wave of COVID-19 cases.
Jim Walker, chairman of Cumbria Tourism, told Sky News: "We have been very surprised by Prime Minister Johnson's statement regarding the easing of travel restrictions.
"We believe this could have severe implications for Cumbria, for our NHS and for those who live in the county.
"Cumbria has one of the highest infection rates for coronavirus in the UK.
"The arrival of many day visitors could easily compromise all the really good work that has been done to date to manage the current situation.
"We are therefore continuing to promote the message that Cumbria is closed to visitors, although we really look forward to the time that our businesses will reopen and we can welcome people back to our beautiful county."
Shortly after the PM's national address, Cumbria's tourism board tweeted: "We are shocked by the timing and short notice of tonight's announcement.
"We are awaiting further details but the safety of residents must come first.
"For now, tourism businesses in Cumbria remain closed and we urge everyone to continue to #StayHome."
Mr Walker's sentiments were echoed by Malcolm Bell, chief executive of Visit Cornwall, who said his message to residents in England remains: "Stay home".
He told Sky News: "We do not believe the government announcement means carte blanche - total freedom - for anyone travelling from outside the county for a day visit.
"There is nowhere to stay. There are very limited places to eat, other than takeaways.
"We do not believe that this is staying alert - to undertake a long, unnecessary journey."
He said he would be seeking clarity and further guidance from the government on what the changes to the lockdown actually mean.
"It is vital to evaluate the plan and its impact on tourism, but also the residents of Cornwall and our communities," he said.
"We are totally committed to play our part in protecting local residents and communities in Cornwall - alongside protecting the future of the industry.
"At this time we ask you to stay away, and in the comfort of your own home, plan a future break to Cornwall when it is safe to do so."
Cotswolds Tourism told Sky News: "We hope that this week's ministerial briefings will clarify the situation. We assume that the prime minister meant (and the briefings will make clear) that people are free to enjoy any parks and beaches near to them: where social distancing should be possible.
"However, with hospitality businesses closed until at least July - along with many car parks and public toilets - it is hard to see how or why anyone could/should travel far from home.
"We certainly won't be encouraging anyone to visit the Cotswolds before hospitality businesses are open to welcome them."
People are not allowed to cross the borders to Wales or Scotland for leisure activities where similar changes to the lockdown have not been agreed by the devolved administrations.
Holiday resorts across England remain closed, and have no idea what the summer holds for them, with Mr Johnson's blueprint for the future currently running up to the beginning of July, when it is being considered non-essential business such as pubs, cafes and restaurants could reopen