The rapid rise in cases in Norfolk came as a surprise, a UEA expert has said, adding that a national lockdown looks “inevitable”.

Professor Paul Hunter, a medical professor at the University of East Anglia (UEA), said despite case numbers rising in the region,it was not as bad as he was forecasting two to three weeks ago.

It comes as the prime minister is expected to announce on Monday a nationwide lockdown for England, which could last a month to try and reduce infection.

A recent meeting of the Scientific Advisory Group for Emergencies (SAGE) found the rate of infections and hospital admissions was now “exceeding the reasonable worst case scenario planning levels”.

Professor Hunter said: We are in Norfolk compared to most parts of the UK very lucky really in terms of case numbers and that doesn’t mean we will stay lucky forever.

More: Norfolk could be like Liverpool ‘in a month’ without Covid-19 circuit breaker, says UEA professor“I was really surprised how rapid cases increased in the last two weeks of September. I always believed they would go up I did not think they would go up as quickly as they did.

“I think it is inevitable we will go for some form of national lockdown. If we have exceeded our worse case scenario we are in uncharted territory. We are on a map which says here be dragons.”

Professor Hunter said the advantages of a national lockdown included no confusion on what the rules were, as seen during the initial period in March and April.

He said the government could look at local authority variations which could pose the risk of people migrating to the area, increasing the chance to bring the infection with them.

More: Second lockdown: Will it happen and what would it mean?Prof Hunter said: “The cons are that areas possibly like Norfolk, which might have been able to operate in a lower level of restrictions will have their economies damaged.

“If we are in a lower tier and then everybody around is in tier three what will happen is people will migrate.”

He said it was not all doom and gloom, with analysis of case numbers of areas under tier three showing signs of decrease and levelling-off.

Professor Hunter said: “There is some evidence, we do not know for certain, but the northern towns that saw much of the increase at the end of September, early October are slowing.

“Liverpool is seeing a decline in cases, and if that is the case it could be seen that tier three is working.”

More: ‘Not warranted or wanted’ - what do our MPs think of a potential second lockdown?Looking at Norfolk’s rise in cases, he said he thought the county was a “borderline case” for tier two, following the increase in Norwich and the outbreak at Cranswick County Food in Watton.

He said: “I think Norfolk is a borderline case. Two weeks ago I would have been really thinking Tier One isn’t going to be enough for us, I’m not so sure now.”

During the first wave of the virus, he said the implementation of lockdown benefitted Norfolk before a surge in cases could occur.

He said: “Our hospitals in Norfolk could have coped with a lot more cases than they actually did [during the first wave]. Norfolk has a lot going for it, it’s a rural county, low population density, it does have areas of deprivation but compared to most parts they are pretty small in comparison.

“Early in October we have in Norwich a rapid increase in the number in cases day to day, they have levelled off a bit.

“It is not looking as bad as it could have been and not as bad as I had forecasted two or three weeks ago.”