Image copyright Charlie Chan Image caption Charlie Chan says both of his careers are about people

Why settle for just the day job?

Charlie Chan is a breast cancer and melanoma surgeon. He is also a rock star photographer.

"My patients always come first so I work full-time as a surgeon and photography is my night job," he says. "I decided to become a surgeon at the age of 12 and concentrated on that."

But photography had been a passion of his since he was 15, and so he started smuggling his Leica camera into gigs.

He got his first press pass from the Cheltenham Jazz Festival and started music photography work 10 years ago.

His subjects include musicians Jamie Cullum, Gregory Porter and Wilko Johnson, who was encouraged by Mr Chan to seek a second opinion after he had received a terminal pancreatic cancer diagnosis in 2013.

Mr Chan arranged for Johnson to see surgeon Emmanuel Huguet, who later operated to remove the tumour and save his life.

Image copyright Charlie Chan Image caption Charlie Chan with musician Wilko Johnson (c) and Emmanuel Huguet, the surgeon who performed Johnson's life-saving operation

You would think that being a surgeon would be more than enough career-wise for most people, so why pursue another profession?

Mr Chan says he uses similar skills in both professions. When shooting in black and white, he sees "light and composition which helps my day job, when performing a breast reconstruction, as you appreciate light and form in the same way".

For Mr Chan, both careers are about people. He wants his photos to tell a story and for the "viewer to be there in the moment", while he says a rewarding and wonderful part about being a surgeon is being able to share good news with his patients who are "very brave in the face of adversity".

Image copyright Charlie Chan Image caption Jamie Cullum and Gregory Porter have been snapped by Mr Chan

Mr Chan is not alone in his "dual career". While some people take more than one job out of financial necessity, many people are doing so out of choice and for the challenge.

Professional networking website LinkedIn has seen a growing trend in the registering of "multiple", "dual" and "portfolio" career descriptions.

Just look at George Osborne: MP for Tatton, adviser at BlackRock Investment Institute, and soon-to-be editor of the London Evening Standard.

Image copyright Rupert Toovey Image caption Rupert Toovey has been working as an auctioneer for his entire adult life

Rupert Toovey founded Toovey's auctioneers in 1995. Fifteen years later he was ordained as a deacon.

The Reverend Rupert Toovey says his secular work is as vocational as his work as a deacon, with each supporting the other. From his late teens, his faith and auctioneering work went hand in hand.

"To serve and listen to people has been a constant thread," he says. "Each role is simultaneously rewarding and vocational."

On visits to people's homes to view antiques, Mr Toovey says: "The objects reflect the patchwork of their lives and it is a privilege to be invited to share these precious moments with them.

"As with the priestly work, I accompany people in profound moments of change in their lives in a particularly personal and private way."

Image copyright Rupert Toovey Image caption The Reverend Rupert Toovey finds parallels between his religious and auctioneering work

He says his life has "a wholeness that fits together in a most unexpected way".

The majority of people Mr Toovey attends to, baptises and marries, are people he has met through the network of his business life, including the Lord Mayor of Westminster.

"Modern society too often compartmentalises life. I am at once a father, priest, auctioneer, employer, [and] friend," he says.

Image copyright Getty Images Image caption Former Chancellor George Osborne has lots of lucrative lines of work

Professional careers adviser Rachel Brushfield says some people look for more than one career because they "want a better work-life balance, more meaning and purpose".

The ability to be "as dynamic as the workplace" and the autonomy of designing your own "stimulating future-proof career" are motivating factors for her clients.

In 2007, New York Times columnist Marci Alboher popularised the term "slash careers" - as in surgeon/photographer - citing creative fulfilment and diverse skillsets as benefits for employers and employees.

But people taking second jobs has been a trend for decades.

According to the Office for National Statistics, the number of people with second jobs has stayed roughly between 1.1 million and 1.3 million since 1993.

Official statistics no longer break out earnings figures. However, looking back, in autumn 2001, men with a second job earned more on average in their main job than those with only one.

Image copyright Duncan McNair Image caption Lawyer Duncan McNair: "They aren't jobs, they are component parts of my heart and soul"

One high earner with several jobs is Duncan McNair, a commercial lawyer, author and elephant campaigner.

He founded the charity Save the Asian Elephants in 2015 and has always written creatively.

Taking cases before the European Court of Human Rights, chairing a review of the RSPCA's welfare scheme, and writing satire, all use his advocacy skills, stretching them further than legal practice alone.

Mr McNair finds his skills "built around the law to be hugely useful in campaigning" for elephants.

While working at Cubism Law and undertaking extensive pro-bono work, Mr McNair donates proceeds from his satirical book series, The Morello Letters, to Save The Asian Elephants.

"The practice takes the majority of time and the rest is filled drafting articles, speeches and writing the final third of the latest Morello book," he says.

"Ideas for the letters come to me while waiting for buses, as sparks of the imagination, explaining my fanatical relationship with post-it notes."

The Morello world offers a "nirvana of humans and animals living in humorous harmony", with a rich source of characters he often finds in the legal profession.

"I'm incredibly lucky to be able to advocate for these causes and to have a various workload. They aren't jobs, they are component parts of my heart and soul."