It started with the Labour Party on the receiving end of a mocking on social media after tweeting Happy St George's Day on Bank Holiday Monday.

Then Prime Minister Theresa May appeared to correct the error by dutifully posting on Twitter to her 830,000 followers this morning: ''The St George’s Cross flies above Downing Street today to mark the feast day of England’s patron saint.''

Now the Church of England has waded in to let the politicians of the country know they have all got the date wrong.

St George's Day does not fall on the usual date of April 23 this year but April 29.

Church rules state that in order to prevent an overlap with a major festival like Easter, if a saint’s day falls during Easter week, it is “translated” to the following week.

Matthew Salisbury, the Church of England’s national liturgy and worship adviser, explained: “St George’s Day is translated to April 29 as nothing other than a principal feast would take place during Easter week.”

A spokesman for the Church of England added: "To protect major festivals from overlapping, the saints days of St George and St Mark must be postponed.

"When St George’s Day or St Mark’s Day falls between Palm Sunday and the Second Sunday of Easter inclusive, it is transferred to the Monday after the Second Sunday of Easter, in this case the week beginning April 29.''

Labour's embarrassing tweet posted Bank Holiday Monday which was taken down and re-posted on Tuesday. Credit: The Labour Party

According to the history books, April 23rd is believed to be the day that St George died.

Although St George's Day used to be a national holiday and major celebration in England, the tradition appears to have died out in the 18th century.

However the Labour leader Jeremy Corbyn has said he wants to introduce new bank holidays to mark the patron saints of England, Wales, Scotland and Ireland if the party wins the next general election.

A report in the The Guardian has revealed Corbyn is set to tell the conference of the Communication Workers Union in Bournemouth on Monday April 29th that Britain’s workers deserve more days off.

Under Labour’s proposals, UK-wide public holidays would be held on St David’s Day (1 March), St Patrick’s Day (17 March), St George’s Day (23 April) and St Andrew’s Day (30 November).

It has been reported that Corbyn is expected to tell the conference: “If we win the next election, St George’s Day will become a national holiday for Britain’s workers. It will be a day where we can all show our pride and celebrate our country’s tradition of fairness, inclusivity and social justice.

“Eight years of Tory austerity, which Labour will bring to an end, have had a disastrous effect on our vital public services and workers have paid a heavy price in the cost of living and their working lives. We will give our workers four extra days’ paid holiday.”

A mannequin is dressed as St. George, the patron saint of England in Warminister in Wiltshire as the town celebrates St George's Day in 2010. Credit: PA

What are the facts about St George?

He may be regarded as England's national hero but St George is believed to have been born in Cappodocia (modern day Turkey) and to have died in Lydda (modern day Israel) in the Roman province of Palestine in AD 303.

St George was a soldier and not a knight as he is portrayed in popular culture. From the 11th century St George was depicted in sculpture as a knight or a warrior on horseback, however, according to English Heritage it is more likely that he was an officer in the Roman army.

While it's highly improbable that St George came to England, his reputation for virtue and holiness spread across Europe from about the 7th century.

Richard I placed himself and his army under the protection of St George during the Third Crusade in the 12th century. He also adopted the emblem of St George, a red cross on a white background, which was worn as a uniform and later used on the English flag.

Like many saints, St George was described as a martyr after he died for his Christian faith.

The famous tale of St George slaying a dragon is likely to be an embellishment. It was popularised in the late 13th century in Jacobus de Voragine's The Golden Legend, which was a compilation about the lives of saints. The story unfolds that St George rode into Silene (modern day Libya) to free the city from a dragon who had a taste for humans. The Golden Legend was translated and published in English in the late 15th century.