Image copyright Aleksandr Petrosyan

An elderly man, his chest heavy with medals, cuts a lonely figure in front of hundreds of onlookers on the route of a parade. He is wiping a tear from his eye. Maybe the flowers he holds are a gift from a grateful nation or his tribute to fallen comrades. It's a scene which has touched many hearts on social media.

A popular Facebook meme claims that the man is the last surviving member of his World War Two battle group. The photo has gained more than one million likes on Facebook, most notably on HypeDojo and UNILAD - both of which are more associated with boisterous banter.

The comments show almost unanimous sympathy and appreciation, despite some confusion about the man's nationality. Perhaps because of the ambiguous caption, readers from a variety of countries have claimed the man as their own.

Image copyright Shirley J. Burkes / Facebook

Image copyright Eddie Dwight / Facebook

Image copyright Vivian Thomas / Facebook

So where was the photo taken and who does it show? There are several clues that reveal that the answer to the first question is almost certainly Russia. The tricolour flag hangs in the background, and the medals are Russian. This does indeed point to Victory Day, an annual holiday commemorating the capitulation of Nazi Germany to the Soviet Union in 1945, at the end of what is known in Russia as the Great Patriotic War.

Image copyright Courtney Hazelton / Facebook

Image copyright Marc Maloof / Facebook

To some the man's nationality doesn't matter, in recognition of our shared humanity, they were happy to pay their respects to a man who risked life and limb to defeat Nazism.

Image copyright Jodie Reid / Facebook

Image copyright Alfred Bable / Facebook

Some sites have credited the image to Aleksandr Petrosyan, a well-known photographer in the St Petersburg area who has many followers on social media. He confirmed to BBC Trending that he took the photo during the St Petersburg Victory Day Parade in 2007 - specifically on Nevsky Prospekt, the main street in the city.

But beyond that he can't shed any more light on the identity of the veteran. "I didn't speak to him, I just shot [the photograph]" he said.

Petrosyan was already aware that his photo had become a viral meme, it has been circulating on Russian social media and garnering a similar reaction for years. However, it's not clear why it has now surfaced outside Russia. But Petrosyan feels the photo has moved so many because of its depiction of "sincere human emotion".

"Canned feelings and energy: If they are transmitted by the picture - it has reached its goal" Petrosyan told Trending.

Image copyright Marlon B. Ibona / Facebook

Image copyright Blink Light Year / Facebook

To try to track down the subject of the photo Trending contacted the St Petersburg Veterans association, but to no avail.

So at Trending's request, Petrosyan reposted the photo on his Facebook page to see if anyone could identify the man. The post gained traction, prompting a discussion about whether the man looked old enough to be a World War Two veteran. Nobody was able to confirm who he was - although one person did recognise him from another photo taken on the same day by another, unknown, photographer.

Image copyright Olessia Islamova / Facebook

So could the man be a veteran of World War Two?

Dr Igor Sutyagin, a Russian military expert at RUSI told BBC Trending that it's possible the man was as young as 75 in the photo. "The usual minimum age for conscription to the Red Army was 17", he said. So if the man had joined in spring 1945 that would make him 79 on Victory Day 2007. But it's possible the man could have been younger. "He could be as young as 13 if he was one of the Sons of the Regiment" Sutyagin added. These were orphan children adopted into the Red Army, who saw combat alongside their adult comrades.

So do the man's medals provide any more information?

Image copyright Aleksandr Petrosyan

According to Sutyagin, the medal worn on his right is "The Order of the Patriotic War" handed out by the Soviet Union to those who played a part in the Soviet Army during World War Two. The other clearly visible medals are anniversary medals.

Image copyright Creative Commons

It is unlikely that the man would have been a senior ranked soldier - especially unsurprising had he been a teenage combatant. Officers commonly wear military outfits to the Victory Day parades, but it is not unusual for those who were more junior in rank to wear informal attire.

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So is the man the last remaining of his battle unit? Without identifying the man it's impossible to say. But one thing is for sure, there are an ever dwindling number of surviving World War Two veterans - a reality captured in another iconic Russian photo.

Image copyright Unknown photographer

The above photo shows Belarusian Konstantin Pronin at the 2011 Victory Day parade in Moscow. He had attended every parade since the end of World War Two, but that particular year none of his comrades turned up.

Image copyright Aleksandr Petrosyan

The US National World War Two Museum in New Orleans estimates that approximately 430 American veterans of that war currently pass away every day, or one every three minutes - with only 700,000 remaining of the original 16,000,000. It estimates that in 20 years none will be left.

We may never know the name of the elderly soldier whose image has touched so many, but if anybody does have any information about the unknown veteran, please contact alex.dackevych@bbc.co.uk

Blog by Alex Dackevych

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