Here's how that British single mum could have really struck it rich as an amateur royals paparazzi

A single mom who snapped a photo of Kate Middleton, Prince William, Meghan Markle, and Prince Harry on the street is hoping to make enough bank from its sale to send her daughter to college.

On Monday, as the royals — dubbed “The Fab Four” on social media — headed to Christmas services at St. Mary Magdalene Church on the queen’s Sandringham estate, fans lined the streets to take photos.

A woman in the crowd named Karen Anvil, 39, of Norfolk, snapped a near-perfect image of the foursome on her iPhone 5. In the photo, Middleton and Will are holding hands and Markle, newly engaged to Harry, is holding his arm. Everyone is smiling and, with the exception of Will, making eye contact with the camera.

“Waiting at Sandringham to see the Royals and got this photo!!!” Anvil captioned the photo, which drew 15K retweets, 1K comments, and 79K likes. Many followers advised her to protect the rare image with a copyright or legal representation, and Anvil admitted she was overwhelmed by the attention.

“I’m just very bubbly by nature, and I was with my daughter and I got a bit excitable, I suppose,” Anvil told the BBC when asked how she captured the moment. “I was just sort of shouting, and I just went ‘Merry Christmas!’ like an idiot. I was fan-girling. That’s all I said, and got them to look.”

It was a hard-earned achievement for Anvil who, last year while she was ill, promised her 17-year-old daughter, Rachel, that they would visit the church, which is famous for drawing the royal family on special occasions, including Christmas.

Since tweeting the photo, Anvil has been inundated with suggestions to sell it — a move she doesn’t necessarily oppose. “The thing is — and I hate to play the single mum card — I’m a single parent; I work two jobs, which I’m proud of, and I’ve always worked,” she told the publication. “Now I want to save money for my daughter for uni, and if I can do that and can get that opportunity, that’s amazing.”

But according to celebrity photographer and media consultant Clinton H. Wallace, while the photo is valuable, the mom has a limited time to cash in. “The image is good — it’s properly composed and the subjects are smiling and looking at the camera,” Wallace tells Yahoo Lifestyle. “But there’s a specific protocol if the owner wants to be compensated.”

For starters, to maximize the value of photos, amateur shutterbugs should keep them off social media. “This woman posted it on Twitter, which makes it breaking news and fair game for any publication to use, as long as they credit her,” says Wallace. “That’s good for exposure, but the photo has less monetary value if it’s been published everywhere.”

Ideally, Anvil would have registered the photo with a large newswire agency — such as Getty Images or Splash News —which would archive it in a database, charge publications a fee for its use, and pay the owner a percentage of its earnings. “In that case, the photographer would be in a very good financial position, especially since pictures of royals have long lifespans,” Wallace said.

Anvil is now directing her Twitter followers to the photo agency GOFF Photos, a British-based company founded by royal photographer Ken Goff, who told Yahoo Lifestyle the company is acting as Anvil’s agent and syndicating the image.

Good luck to Anvil, who is clearly ending 2017 on a picture-perfect note.

Read more from Yahoo Lifestyle:

• This creepy nail art with blinking, movable eyes is being called ‘nightmare fuel’

• How this savvy mom found a dangerous substance in her daughter’s makeup kit from Claire’s

• Melania Trump slammed for ‘incredibly tacky’ Christmas selfie

Follow us on Instagram, Facebook, and Twitter for nonstop inspiration delivered fresh to your feed, every day.