A prison officer has tested positive for coronavirus.

The male officer from HMP High Down, in Surrey, is thought to be the first person in a British prison to have tested positive for the disease.

A Prison Service spokesperson said: ‘One prison officer at HMP High Down has tested positive for Covid-19 and is self-isolating at home.

‘No other staff and no prisoners have tested positive.

‘The prison is operating as usual and our dedicated prison staff are taking all necessary precautions to prevent the virus’s spread, in line with PHE guidelines.’

Authorities have isolated four prisoners who were in close contact with the guard as a precautionary measure.

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Boris Johnson set out this evening the need for ‘drastic action’ to tackle the ‘fast growth’ of coronavirus across the UK as increased social distancing measures were introduced for the population.

As part of the measures, anyone living in a household with somebody who has either a persistent cough or fever must now also isolate themselves for 14 days.

All people should avoid gatherings and crowded places, while people who are vulnerable – including those who are elderly – will need to undertake even more tough measures.

The Prime Minister said people over 70 will need to self-isolate for at least 12 weeks to protect themselves.

He said by the weekend, those groups particularly vulnerable to Covid-19 will be asked to stay at home to ensure they are ‘largely shielded from social contact’.

The groups have not yet been announced but are set to include over 70s, pregnant women and people with chronic heart disease and kidney disease.

Chief medical officer for England Professor Chris Whitty added: ‘Those are the groups we want to take particular care to minimise their social contact which of course will have very significant risks for them.’

The measures were announced as the death toll of people with coronavirus in the UK reached 55.

Across the country, 1,543 people have now tested positive for Covid-19, up from 1,372 at the same time on Sunday.