As pubs and shops re-opened following months of lockdown the UK recorded a fresh spike in new Covid cases, totalling 3,568 infections.
England also confirmed 13 more deaths from Covid, while other nations of the UK did not record any further deaths.
The rise in coronavirus cases is the highest number of daily cases since April 1 saw 4,479 cases, and is a rise of almost one third since a week ago.
The previous Monday, on April 5, there were 26 deaths in the UK and 2,762 cases.
Cases of Covid have been generally falling since the UK went into its third lockdown in early January.
Researchers recently found there have been “big falls” in prevalence of the virus in the South East and London from February to March.
But there remain “persistent areas of higher prevalence” of the virus in the southern part of Yorkshire, and parts of the East Midlands and the North West.
While 297 of England’s 315 local authority areas have reported a week-on-week fall in infections, experts are worried that the virus could make a resurgence.
On Monday a raft of restrictions were lifted, and many businesses opened their doors again, including pubs, non-essential retail and gyms.
Libraries, zoos and nail salons have also been given the go ahead to re-open as greater outdoor interaction is permitted while mixing with other households indoors remains heavily restricted.
The government says that the next stage of the roadmap out of lockdown will not take place until at least May 17.
Most legal restrictions on meeting others outdoors could be lifted at that point but gatherings of more than 30 people will remain illegal.