Over one million protestors marched in London on Saturday to demand a second Brexit referendum, according to organisers of the event.

The massive rally of people from the United Kingdom flooded London's main streets and marched towards the parliament building on Saturday, March 23.

It comes in a tumultuous week for Brexit that saw UK Prime Minister Theresa May ask Brussels to extend the UK's deadline for leaving the EU.

Huge crowds opposed to Britain's current trajectory marched from Marble Arch to outside the UK parliament in Westminster.

Marchers in the British capital carried European Union flags and placards praising the longstanding relationship between Britain and continental Europe.

The protest drew people from all across Britain who are determined to force Prime Minister Theresa May's government to alter its march toward Brexit.

This outcry coincides with a record-breaking petition – which is approaching five million signatures in under four days – to call on the UK to revoke Article 50 and remain in the EU.

According to the relevant laws and regulations of the United Kingdom, once a petition exceeds 10,000 signatures the government must respond publicly and if the number of signatories surpasses 100,000 then parliament must conduct an open debate on the matter.

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Joining the protest was First Minister Nicola Sturgeon who says Scotland — which voted overwhelmingly to stay in the EU — has been ignored by the UK government.

London's mayor, Sadiq Khan, also participated in the march and has made it clear he supports revoking Article 50 to end this "Brexit disaster".

Last Saturday, Brexiteers begun the "March to Leave" from Sunderland to London to stop what they see as "Brexit betrayal". Encouraged by former UKIP leader Nigel Farage, around 200 Brexit supporters began a 270-mile march from Tyne and Wear to the British capital.

A week in, the walk is nearing the Midlands city of Nottingham and leavers are expected to arrive in Westminster on Friday, March 29, the original date the UK was meant to leave the EU.

The European Union on Thursday extended the original March 29 Brexit deadline after a series of meetings in Brussels with PM May.

The EU has offered the UK a choice of two possible extensions to Article 50, which sets out the process for leaving the EU:

April 12: the date the UK is set to leave if MPs do not approve the exit deal. The date has been chosen because April 11 is the UK's own legal deadline for taking steps to take part in EU elections. By then, the UK will have had to say what it intends to do: perhaps request a further delay which would mean holding EU elections, or leave the EU without a deal.

May 22: the date the UK will leave the EU if parliament approves the deal. This is to allow time for ratification and is the day before voting begins in the European Parliament elections.

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