A plane carrying a banner displaying the slogan “Take Control #VoteLeave” has repeatedly flown over Trafalgar Square as Jo Cox’s husband gave an emotional speech at a rally in her memory.

Brendan Cox was telling crowds how the killed Labour MP “lived for her beliefs” and would have been spending the day campaigning for Britain to remain in the European Union.

Thousands of people were gathering at events in London, across the UK and around the world to pay tribute to Ms Cox's life and legacy on what would have been her 42nd birthday.

Many of those rallying in Trafalgar Square condemned the appearance of the pro-Brexit plane as “disgusting”, saying the banner flew over the rally several times as the memorial continued.

One person called the appearance “unbelievably tasteless”, while another said it was “completely disrespectful”.

Stella Creasy, the Labour MP for Walthamstow, wrote a tweet to the official Vote Leave campaign saying: “Flying your plane over the memorial tribute to Jo Cox in Trafalgar Square is beyond low. Have some self respect and disappear!”

Jo Cox's birthday celebrated

She added: “It's been over twice now - that isn't coincidence @voteleave , that's just sickening disrespect!”

Vote Leave said it did not organise the plane, which had been dispatched by British aircraft manufacturer Britten-Norman as part of its own pro-Brexit campaign.

Brendan Cox, widower of Jo Cox addresses the rally in Trafalgar Square, on what would have been the 42nd birthday of the Labour MP (PA)

In a press release announcing the stunt, the firm said its banner would be flown around the UK between 9 June and the day before the referendum from a turboprop Islander aircraft.

"We understand that, during a pre-planned photo opportunity over Westminster today, we were visible from Trafalgar Square and that our flight coincided with an important memorial service,” a spokesperson said.

"The timing of our flight was determined by weather, air traffic control and the prior approval of the the Diplomatic Protection Group and required the consent of the Metropolitan Police.

"We are clearly very disappointed that the timing of the service and our flight have overlapped but there was no NOTAM (Notice to Airmen) requesting the avoidance and the coincidence of timing could not have been known by the crew flying the sortie.

"Our sincere apologies to anyone present who has been offended by the overflight. We would also like to take the opportunity to advise that the flight was a private one and was not sanctioned by the official Vote Leave campaign.”

The plane's engines could be heard as Mr Cox fought against tears in an emotional tribute to his late wife.

Brendan Cox, husband of Jo Cox, and their children ride on the boat towing a memorial dedicated to the Labour MP down the River Thames (Getty Images)

“Your support and your love has helped us all,” he told the crowds. “Today would have been Jo’s 42nd birthday and she would have spent it dashing around the streets of her hometown trying to convince people that Britain is stronger in Europe.”

He said the Labour MP would have been “amazed, baffled and humbled” at the global reaction to her death and the “outpouring of love from around the world”.

A minute’s silence was held during the hour-long celebration of her life, which was also attended by her three-year-old daughter Lejla and son Cuillin, five.

Malala Yousafzai, the education campaigner who was shot in the head by the Taliban for her activism, was among the guest speakers at the rally.

Events were being held in a variety of locations in tribute to Ms Cox's “love, energy, passion, flair, Yorkshire heritage and belief in the humanity of every person in every place”.

Bill Nighy was due to give a reading, while U2 had recorded a musical tribute in Los Angeles.

Jo Cox tributes - in pictures Show all 20 1 /20 Jo Cox tributes - in pictures Jo Cox tributes - in pictures Floral tributes and candles are placed by a picture of slain Labour MP Jo Cox at a vigil in Parliament square in London AFP Jo Cox tributes - in pictures Tributes to Labour Party MP Jo Cox are placed on her houseboat in Wapping in London REUTERS Jo Cox tributes - in pictures The Union flag at half-mast on top of Portcullis House in London after Labour MP Jo Cox was shot and stabbed to death PA Jo Cox tributes - in pictures Labour leader Jeremy Corbyn (2R) and deputy leader Tom Watson (L) light candles as they attend a vigil to slain Labour MP Jo Cox in Parliament square in London AFP/Getty Images Jo Cox tributes - in pictures Labour Party leader Jeremy Corbyn and deputy leader Tom Watson (rear) arrive to leave tributes at Parliament Square PA Jo Cox tributes - in pictures People leave St Peter's Church after a vigil in memory of Jo Cox REUTERS Jo Cox tributes - in pictures Flowers left at Parliament Square opposite the Palace of Westminste, following the death of Labour MP Jo Cox PA Jo Cox tributes - in pictures People react as they look at tributes left for Labour Member of Parliament Jo Cox in Parliament Square, London REUTERS Jo Cox tributes - in pictures A man writes a message at Parliament Square PA Jo Cox tributes - in pictures People stop to look at tributes left at Parliament Square opposite the Palace of Westminster PA Jo Cox tributes - in pictures A woman arrives to lay flowers at a statue to Joseph Priestly in Birstall near to the scene where Labour MP Jo Cox was shot AFP/Getty Images Jo Cox tributes - in pictures Tributes at Parliament Square opposite the Palace of Westminster PA Jo Cox tributes - in pictures A woman places candles in tribute to Labour Party MP Jo Cox REUTERS Jo Cox tributes - in pictures A member of the public signs a memorial for British MP Jo Cox in Parliament Square, London EPA Jo Cox tributes - in pictures People sign messages of condolence for MP Jo Cox during a vigil in Parliament Square in London Getty Images Jo Cox tributes - in pictures Flags at half mast outside Scottish Parliament in Edinburgh, after Labour MP Jo Cox was shot and stabbed to death in the street outside her constituency advice surgery in Birstall PA Jo Cox tributes - in pictures People arrive in Market Square with floral tributes after the death of Jo Co Getty Images Jo Cox tributes - in pictures Floral tributes are placed in Market Square next to the statue of Joseph Priestley following the death of Jo Cox Getty Images Jo Cox tributes - in pictures Floral tributes are brought to the scene after the death of Jo Cox Getty Images Jo Cox tributes - in pictures A police officer carries bunches of flowers at the scene of the shooting of Labour MP Jo Cox in Birstall REUTERS

The band that played at the couple's wedding, Diddley Dee, also performed and a group of the MP's friends will form an honour guard dressed in suffragette-style sashes.

Leaders of multiple faiths were to lay 42 white roses, the symbol of Yorkshire, to mark her birthday at the event, hosted by Mrs Cox's friend, Mariella Frostrup.

International events were also taking place in Beirut, Brussels, Melbourne, Nairobi, New York and Washington DC.

Glastonbury's Park Stage will be the location of one tribute, while a charity album of music recorded by bands including Coldplay and Muse at the festival this weekend will be released in her honour.

It came after a fundraising page in Mrs Cox's memory raised more than £1 million for three of her favourite charities in just three days.