Thousands of foreign workers in Colchester and Tendring are key workers.

The GMB union has warned the Government’s points-based immigration system, which is due to be introduced in January, could leave the UK "desperately short" of key workers.

According to researchers at Oxford University, many key workers will not qualify for a work visa.

Office for National Statistics figures reveal that out of 10,700 non-British workers estimated to be in employment in Colchester, 4,800 were working in key roles between 2017-19.

That is 14 per cent of the 34,100 total key workers in Colchester.

In Tendring 600 non-British workers were in key roles between 2017-19 - this is 3 per cent of the 21,900 total key workers in the district.

Key workers are employed in sectors deemed essential by the Government, such as health and social care, education, food production, transport and other public services.

Rehana Azam, GMB National Secretary, said: "Health and social care, for example, rely heavily on workers from abroad. We have huge numbers of vacancies and the current workforce is already under incredible pressure."

A spokesman for the Home Office said: “The Government is committed to delivering a firmer, fairer, points-based immigration system, based on the skills people have and not where they come from.

“We have removed the Resident Labour Market Test to make it easier for employers to sponsor workers and suspended the cap on skilled migrants.

“We are also introducing special schemes to enable more scientists, academics, investors, entrepreneurs, and health and care workers to come to the UK easily, so that we can work with sectors to fill roles quickly where shortages may occur."