Thousand of lockdown fines issued in England and Wales have gone unpaid, new figures show.
Some 18,646 enforcement letters have been sent out and a staggering 9,413 have not been settled.
While some of the people have formally contested the sum, others are being considered for prosecution.
It comes as National Police Chiefs’ Council (NPCC) chairman Martin Hewitt said that as new regulations are brought in, forces in England and Wales are expecting the number of fines issued to increase.
Mr Hewitt said: “We anticipate there will be an increase obviously as regulations are introduced in different parts of the country.
“The FPNs (fixed penalty notices) were designed in the way that a number of other FPNs are and every individual has the right to decide not to pay that fine and elect to go to court and plead their case.”
There is no formal right to appeal, although some local authorities may allow representations to be made if the fine is contested.
The person also has the option of refusing to pay and waiting to get taken to court, although they may then lose and end up paying more.
Data published by the NPCC on Wednesday also showed that hundreds of travellers suspected of breaking quarantine rules had not been traced.
Up to September 22, 4,114 cases were referred to police by health authorities, including 240 where people were found not to live at the address they had given, and 440 cases where there was no answer when officers attended an address.
Figures showed 3,216 were found to be complying with self-isolation rules, and 218 were found to be in breach but were spoken to by officers to encourage them to comply.
Police issued 38 fines to those failing to self-isolate after returning from a country on the Government Quarantine List.
Mr Hewitt admitted there is no “foolproof system” to stop people flouting the rules and said that stretched forces would not get into a “manhunt scenario” to find people who are not self-isolating.
“We have to be reliant that most people will be responsible, will accept that personal responsibility and will be sensible, but equally, there also has to be a response that is proportionate,” he said.
“It also has to be something that’s within the capacity of the service to deliver against when we have all the other demands that we have.”
The NPCC said that just 15 fines were handed out in England in the first week of the “rule of six” lockdown regulations, although this number could increase when figures are updated.
In the seven days from September 14, four fines were issued by Greater Manchester Police; seven by Lancashire Police; two by Leicestershire Police; and two by West Yorkshire Police.
In total, 18,912 lockdown fines were issued in England and Wales between March 27 and September 21.
In the final four weeks of that period, 147 fines were issued in England and four in Wales.
Eighteen fixed penalty notices for breaking rules around large gatherings including illegal raves and parties, that carry a £10,000 penalty, have been issued in England and two in Wales.
Police have given 61 fines for failing to wear a face covering on public transport, up from 38 up to the middle of August, while 28 were handed out for not doing so in shops.
Mr Hewitt said: “It is crucial that people do everything they can, including limiting social contact, to reduce the spread of coronavirus. The country is at a critical point, and personal choices will matter in the weeks and months to come.
“Thank you to the vast majority of the public for sticking to the rules and following the guidance in place to limit the spread of the virus.
“A small minority, however, are not following the rules, and are making decisions which put lives at risk – they should expect to have enforcement action taken against them.”