Why is everyone in Britain wearing a red poppy?

It's a symbol as rooted in the British autumnal calendar as Halloween and Bonfire Night: the poppy.

Walk down any high street at the start of November and you’ll see artificial poppies attached to coats and jumpers, in shop windows, or on car grills as an act of remembrance to Britain’s war dead. This year they're held in even greater significance, as this summer marked the 100th anniversary of the start of World War I.

But why the poppy? And who benefits from its poignant symbolism which seems to cross age, class, and most cultural divides?

What does the poppy mark?

In Britain, and to a lesser extent some of its former colonies such as Canada and Australia, the red poppy is the symbol for Remembrance Day, which marks the deaths of armed forces personnel. It falls on the Sunday nearest to Armistice Day (Veterans Day in the US) on Nov. 11, and features services in churches and war memorials across the country.

While the date originated from the end of World War I, Remembrance Day recognizes the deaths of all men and women in Britain’s armed forces including recent conflicts such as Iraq and Afghanistan.

Why a poppy?

The roots of the Remembrance Day poppy are literally in the trenches of the Western Front during World War I. Despite the devastation of battle when landscapes turned to mud under heavy shelling, the red poppy grew in abundance – an irony of life amid death.

In 1915 after losing a friend in the Second Battle of Ypres, Canadian doctor Lt. Col. John McCrae wrote the poem "In Flanders Fields," which cited the poppies' growth over soldiers’ graves. Inspired by the poem, three years later US Professor Moina Michael began making handmade red silk poppies which she sold to friends. The poppy was then popularized in England and France by French woman Anna Guerin, who promoted sales of cloth versions of the flower to help the needy.

How big a business are Remembrance poppies?

In its first ever "Poppy Appeal" in 1921, the Royal British Legion – which provides welfare and support to current and former service people and their families – ordered 9 million of the flowers and raised a then huge £106,000.

The appeal now runs every year in the weeks leading up to Nov. 11, and centers on the simple lapel poppy, of which the Legion produces 40 million a year. It will also make 500 thousand poppies of other types such as car grill ones and metal brooches; 100 thousand wreaths and sprays; and 750 thousand Remembrance crosses.

The Legion sends out 350,000 volunteers to sell poppies door-to-door or in the street. While brooches and car grill poppies have fixed prices, there is no set price for the simple lapel poppy: the buyer decides. Last year, the event raised £39 million ($62 million) for the Legion; this year's take is expected to be similar.  

Why all the to-do lately over the poppy?

The poppy is supposed to be an apolitical symbol to memorialize British military losses. But populists have begun to use it as a political football – both as a proxy for flag-waving and as a litmus test for patriotism.

Exhibit A: an art installation in the moat of the Tower of London. The display, called the Blood Swept Lands And Seas of Red, features 888,246 ceramic poppies representing each British and colonial death during World War I.

Since its installation in August, the exhibit has attracted an estimated 4 million visitors. The individual poppies have all been sold at 25 pounds ($40) each, with the proceeds going to various armed services charities. And the exhibition has proven so popular that part of it will remain in place for two weeks beyond its initial end date, Nov. 11.

Not all are pleased. Guardian newspaper art critic Jonathan Jones recently dismissed it as "fake, trite and inward-looking" and the sort of art "that lets UKIP thrive" – referring to the anti-EU, populist UK Independence Party. A few days after the review appeared, UKIP leader Nigel Farage visited the site and was seen wiping away a tear.

Wearing the poppy has also become something of a test of patriotism, like flag lapel pins in the US. Television presenters Jon Snow and Charlene White have come under fire for their decision not to wear poppies during their broadcasts, which critics say shows a "lack of respect" for veterans.

Both presenters have argued that it would be inappropriate to wear one charitable symbol and not others on air; both say they wear the poppies privately. Mr. Snow said the criticism he has received over not wearing the symbol amounts to "poppy fascism."