New laws enforcing lockdown restrictions in areas of the north of England, including Greater Manchester, parts of East Lancashire became effective from midnight.
The Health Protection (Coronavirus, Restrictions on Gatherings) (North of England) Regulations 2020 were published on Tuesday afternoon and came into force this morning.
Ministers had said the rules - which ban people from different households meeting in a private home or garden following a spike in coronavirus cases - would apply from midnight on July 31.
Anyone found flouting the rules could be fined £100 up to a maximum of £3,200 for repeat offences.
Officials refused to comment when asked why there had been a delay in imposing the laws and on what legal basis they had been enforced for the first five days of the measures.
Human rights barrister Adam Wagner, commenting on the legislation on Twitter, said: "They come into force and do not (cannot) apply to anything which happened before that."
The legislation imposes restrictions on metropolitan, city and borough council areas in: Bolton, Bury, Manchester, Oldham, Rochdale, Salford, Stockport, Tameside, Trafford, Wigan, Burnley, Hyndburn, Pendle, Rossendale, Calderdale and Kirklees.
But the restriction zone could change at any time as directed by Health Secretary Matt Hancock, papers setting out the legislation said.
The Regulations also amend existing laws for Blackburn with Darwen and Bradford, which means those areas are now subject to the same measures as well.
The towns and city were initially governed by less restrictive legislation which was made on Friday and came into force on Saturday.
The laws also prohibit people from meeting others from different households in areas outside the lockdown zone, such as at homes in nearby towns not subject to the rules.
People are also not allowed to meet in groups of more than 30 in public places.
The ban does not extend to places such as hotels, campsites and guest houses or include other buildings such as care homes.
There are exemptions to the rules, including: for those who have formed a support bubble and have become "linked" households; for people sharing childcare duties; in order to go to work; to attend a birth at the mother's request; to visit a dying loved one; to fulfil a legal obligation; to move house, to care for a vulnerable person or escape injury, illness or risk of harm.
The restrictions must be reviewed once every 14 days and the first must take place by August 19.
But they could be in place for up to six months if not scrapped by the Government first.