Postal workers formed picket lines across the county as part of “the biggest strike in the UK since 2009”.

The Communication Workers Union (CWU) said its members are taking industrial action for a “dignified, proper pay rise” after they voted in favour by 97.6% in a ballot.

The strike on Friday will be followed by further stoppages on Wednesday August 31, Thursday September 8 and Friday September 9.

The union said management imposed a 2% pay rise on employees, yet they were classified as key workers throughout the Covid-19 pandemic.

Royal Mail said it has “well-developed contingency plans” to minimise disruption, focused on getting mail delivery back to normal as quickly as possible after strike action.

A company spokesman said: “We are losing £1million a day, and we need to change what we are doing to fix the situation and protect jobs.

“This change is also needed to support the pay package we have offered to CWU grade colleagues, worth up to 5.5%.

“This is the biggest increase we have offered for many years and the CWU have rejected it. This would add around £230million to Royal Mail’s annual people costs when the business is already loss-making.”