It is "crystal clear" that drunk people are unable to socially distance, the chair of the Police Federation said as pubs reopened on Saturday.
Ministers had urged caution ahead of hospitality venues reopening in England after three months of lockdown.
John Apter dealt with "naked men, happy drunks, angry drunks, fights and more angry drunks" on shift in Southampton.
But police thanked the majority of people for acting responsibly as they enjoyed the night out.
Hundreds gathered in London's Soho district, with images showing packed streets into the early hours of Sunday.
The Metropolitan Police said that there were "no significant issues" in the capital.
Devon and Cornwall Police received more than 1,000 reports, most of which were "drink-related".
Image copyright Getty Images Image caption Bars on Hilton Street in Manchester's Northern Quarter set out tables for customersIn north Nottinghamshire, four people were arrested and several pubs decided to close after alcohol related anti-social behaviour.
While people were out in droves at thousands of venues, fears emergency services could be as busy as New Year's Eve appear not to have been realised.
But Mr Apter said: "What was crystal clear is that drunk people can't/won't socially distance.
"It was a busy night but the shift managed to cope. I know other areas have had issues with officers being assaulted."
Image copyright Getty Images Image caption Police officers are seen walking through heavy crowds in Soho, central LondonPeople in England are still urged to stay 2m apart, but the new "one metre plus" guidance means they can get closer if they use "mitigation" measures, such as face coverings and not sitting face-to-face.
Boris Johnson and government experts had urged people to stick to the rules to avoid creating a second wave of coronavirus, with chief medical officer for England Chris Whitty saying easing lockdown is not "risk-free".
Image copyright PA Media Image caption Groups gather in Borough Market, LondonIt was a different night for Leicester where the streets were largely deserted as pubs and other venues remain closed after the city became the first to be subject to a local lockdown on Monday, following a spike in Covid-19 cases.
Restrictions on the hospitality sector remain in place in Scotland and Wales, while pubs have been able to open in Northern Ireland since Friday.
The latest figures, released on Saturday, showed a further 67 people had died in the UK after testing positive for coronavirus, bringing the death toll to 44,198.
Despite the relaxation of restrictions, some 30% of bars, pubs and restaurants stayed shut, according to the Night-Time Industries Association, amid fears for safety and concerns over how to implement social distancing guidance.
In England, people are being allowed to stay the night away from home for the first time since lockdown started, with campsites and holiday accommodation also reopening.
Police in Dorset, Devon and Cornwall reported gridlock on the roads on Saturday - including a high volume of caravan owners heading to the coast.
Other rule changes that came into effect on Saturday include allowing two households to meet indoors or outside, including for overnight stays - although they have to maintain social distancing.
Meanwhile, new quarantine exemptions will allow major sporting events, as well as TV and film productions, to go ahead this summer.
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