“We have given the police a series of enforcement powers and will leave it to their discretion how to enforce them,” he said.
Police in Durham and North Yorkshire have begun roadside checks on motorists and pedestrians, questioning them about their reasons for being out during the coronavirus lockdown.
And the Derbyshire force was condemned for taking drone footage of ramblers, dog walkers and people taking pictures in the Peak District.
The prime minister’s spokesperson rejected criticism that the tactics were an overreaction, saying: “Wherever possible, avoid unnecessary travel.”
He argued that the “overwhelming majority of people will fully understand the gravity of the situation” and accepted the need for the crackdown.
It had “always been” the British way for governments to pass laws and leave it up to the police to decide how they should be carried out.
Asked if the lockdown was working, the spokesperson pointed to “strong anecdotal evidence that people are using public transport less”.
The public was told this week to leave their home only for essential shopping, a once-daily bout of exercise, medical need or travelling to and from work where absolutely necessary.
Laws that came into force on Thursday night gave officers the power to issue £60 spot fines that will be reduced to £30 if paid within two weeks.
The fine will double to £120 for a second offence and parents will be deemed responsible for their children.
Derbyshire police defended the decision to deploy a drone to film ramblers and dog walkers, arguing the activity was “not essential” and should be avoided during the lockdown.
Drivers in Shropshire and Devon were left notes on their cars asking “why are you here today?”, adding that they should be walking, running or cycling “from home”, not driving somewhere.
The lockdown has had the benefit of producing big drops in air pollution across the country’s major cities.
New data showed decreases in levels of toxic pollutants of between one-third and a half in London, Birmingham, Bristol and Cardiff, and falls of about a quarter in Manchester, York and Belfast.
For nitrogen dioxide (NO2) pollution, the data also shows declines of a third to a half in London, Birmingham, Bristol and Cardiff, and drops of 10-20 per cent in the other cities.
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