The London Marathon was the brainchild of former middle distance runner Chris Brasher, winner of 3000m steeplechase gold at the 1956 Olympics and one-time holder of the 5000m world record.
Dick Beardsley and Inge Simonsen finish the first marathon together
He returned from taking part in the 1979 New York Marathon an inspired man - and with the seeds of an idea implanted.
Writing about his experience in the Observer, Brasher could not hide his admiration for the event.
"To believe this story, you must believe that the human race can be one joyous family, working together, laughing together, achieving the impossible," he mused.
"Last Sunday, in one of the most trouble-stricken cities in the world, 11,532 men and women from 40 countries in the world, assisted by over a million black, white and yellow people, laughed and cheered and suffered during the greatest folk festival the world has seen.
"I wonder whether London could stage such a festival? We have the course, a magnificent course.... but do we have the heart and hospitality to welcome the world?"
Encouraged by the response he received, Brasher and Observer editor Donald Trelford met with the Greater London Council, the Metropolitan Police and athletics' governing bodies early in 1980.
After studying the organisation and finances of both the New York and Boston marathons, Brasher put together a budget for a similar race in London, and was given a cautious green light by the authorities.
Gilette sponsored the race to the tune of £50,000, and the granting of charitable status to the race was crucial in calming the fears of GLC leader Sir Horace Cutler, who insisted, "You never ask the ratepayers to bail you out."
The chosen date for the inaugural race was 29 March 1981 when
7,747 people accepted as starters from over 20,000 hopefuls.
The race itself was won in exactly the manner Brasher had hoped - the 6,255 finishers were led home by the American Dick Beardsley and Norwegian Inge Simonsen, who chose to cross the line, hand-in-hand, in a deliberate dead heat.
Around 25 minutes later, Briton Joyce Smith won the women's race in a new national record.
A mark of the success of that first London Marathon could be seen the following year. More than 90,000 people from across the world applied to take part.
In the 20 years since that first race in 1981, 445,129 people have completed the London Marathon.
Numbers have continued to grow since that humble beginning.
Last year a record 45,500 competitors entered the race with a London Marathon best 32,899 finishing the course.
A record £31m was raised for charity, confirming that Brasher's vision holds as true today as it did all those years ago.