A mum was grieving her 4-year-old's death. Then an incredible sign brought her to tears.

Just three months after he was diagnosed with a brain tumour in 2014, Jack passed away.

He was just four years old, and left behind an identical twin brother, Liam, and three older sisters.

This week, his mother, 45-year-old Marie Robinson, from Waterlooville in England, was facing the impossible task of commemorating the three year anniversary of her young son’s death.

On Facebook, Marie wrote that she was still as "numb" three years after his death as the day her family lost little Jack.

"Today will be hard, we all miss him," she wrote.

On Saturday, she asked her son for "a sign" to let her know he was safe and happy.

"Early Saturday morning I got in the car and said out loud, 'Please show mummy a sign', and I thought I'll see him after I finished work," Marie told The Mirror.

"At 1pm I left work and walked to his resting place. I was overcome with emotion and I sat on the grass next to Jack."

What happened next brought Marie to tears.

"A little robin kept flying around me trying to land on me, eventually landing on my foot. He didn't seem scared at all," she said.

"I got my phone out to film him being close to me and he flew over and landed on my hand.

"He kept looking at me directly in my face and at one point he landed on my shoulder and nibbled me a couple of times."

Marie shared the video - which has now been viewed an astonishing 10.2 million times - and said she was "taking it as a sign from Jack".

Robins are often seen as a sign as new beginnings and joy in the spiritual community. Some believe that the presence of a robin means that you are being watched and can mean a loved one who has passed is "letting you know that they still love you", reports The Mirror.

Marie now hopes her robin video can help raise awareness of childhood cancer.

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"I have read loads and loads of heartfelt messages from loads of people...I have been very touched with reading peoples stories from people losing a child and adults and not to just cancer," she wrote on Facebook.

"It is unbelievable how much a robin symbolises [for] a lot of people."