The margarine brand previously backed the event as the headline partner from 1996 to 2009 and has signed-on again until 2023 with a new partnership.

This year's London Marathon, with Virgin Money as its headline sponsor, has been re-arranged for October 4 from its original April 26 date due to the COVID-19 pandemic.

Only elite races will be held on a St James' Park loop course in a "bio-secure environment", organisers said.

Mass-participation runners, including many who will be running for charity, will still be able to celebrate the occasion by completing the 26.2 mile distance on a course of their choice from wherever they are in the world.

This year's London Marathon will be the 40th edition of the race, which is part of the World Marathon Majors alongside Tokyo, Boston, Chicago, Berlin and New York.

Flora will support runners who are fundraising for small charities by donating £1,000 ($1,300/€1,100) per week to one lucky participant who shares their story.

Other prizes will also be available including running kit and places in the 2021 race.

Britain's Paula Radcliffe, who won two London Marathon titles and broke two world records when Flora was the headline sponsor of the event, has been named as an official Flora running ambassador to mark the partnership.

She will provide exclusive training and nutrition tips as part of a new "keep running" content hub.

"Everyone has such fond memories of our previous partnership with Flora and we are delighted to be able to renew that relationship," said Hugh Brasher, event director of the London Marathon.

"It is particularly fitting that Flora, which has played such a large part in our history, is back as a partner for the 40th race on Sunday 4 October.

"It says so much about the status of the London Marathon that we are welcoming this new partnership at a time when so many businesses in so many industries are facing an uncertain future."

Britain's charity sector is facing a £10.1 billion ($13.2 billion/€11.1 billion) funding shortfall as a result of COVID-19, according to Probonoeconomics.com,

"We're really excited for Flora to be partnering with the Virgin Money London Marathon," said Flora's marketing director for the UK and Ireland, Catherine Lloyd. 

"Flora has been an iconic and versatile brand within British kitchens for generations and a staple of nutrition plans for runners since the 1960s. 

"Many still remember when the event was known as the Flora London Marathon, so we're delighted to rekindle our friendship and be back in the race.

"As an official partner we plan to support seasoned runners and new-found running enthusiasts with tips from our running ambassador and Flora friend Paula Radcliffe on how runners can balance healthy eating as part of a sustainable, nutritious training diet."

When Flora's headline sponsorship ended in 2009, the company said it wanted to "seek other ways" to challenge public perception about heart health.

Virgin became title sponsor in 2010, before the first Virgin Money London Marathon in 2014.

In October, it was announced that Virgin Money would not be continuing its deal after the 2021 race.

"I am thrilled about Flora coming back on board as an official partner of the London Marathon and delighted to be partnering with them as the Flora running ambassador," said Radcliffe.

"All of my wins in London came when the race was known as the Flora London Marathon and this partnership ties in with my beliefs on healthy living and keeping the family active and eating healthily."