James Murphy has a lot of responsibility on his shoulders. He is behind five Christmas advertising campaigns launching this week that could make or break the festive season for the brands involved.

“It’s a big week for us,” said Murphy. The ad man is the co-founder and chief executive of agency adam&eveDDB, which has produced John Lewis’s Christmas adverts since 2009.

During this period, the department store has set the benchmark for festive marketing campaigns – attracting tens of millions of views online, turning bears, hares and penguins into cuddly toys and generating two number one singles in the UK music charts.

Murphy claimed this year’s campaign could overtake 2011’s The Long Wait – which saw a young boy excited about giving his parents a present – as his favourite.

“It is a lovely, very simple story,” he said of the advert, which features a young girl transporting a present to a lonely man on the moon. “I am the father of a young daughter, so I love it. My favourite is The Long Wait, but I think it might be about to be pipped by this one.”

However, #OnTheMoon is not the only campaign being launched by Murphy this week. He is also overseeing festive marketing drives by Waitrose, Mulberry, Harvey Nichols and, in stark contrast, an advert by Australian cat food brand Temptations.

“We have 48 clients, so there is a great diversity,” he said. “You can have broad, populist, everyday grocery brands like Unilever, and then things like Harvey Nichols, which may be a more niche audience.”

Christmas can account for almost half of a retailer’s sales, which makes this a vital time of year for Murphy and his clients. So what is the key to a successful Christmas advert?

“Something that makes people excited that it is Christmas. Ultimately, what we are doing with our Christmas campaigns is to get noticed and be remembered. Research suggests people go to four or five places when they go shopping – we want to be one of the places they go to.”

The idea for a Christmas ad is agreed months in advance. In the case of John Lewis, Murphy said the retailer and the agency settle on a concept by March. The process starts immediately after the preceding Christmas, when the retailer sets a brief for the advert and the agency then produces a shortlist of three or four ideas. The idea for The Long Wait came from a single sentence in a script for a different story. This was spotted by a creative director at adam&eve, who suggested focusing on the concept of a child being excited about giving a present rather than receiving one.

“We have got a brief that doesn’t change,” Murphy said of his work with John Lewis. “It is the same brief every year about thoughtful gifting. It is based on the truth of John Lewis that they have 300,000 products, which is one of the widest assortments for any retailer. It is about finding a way of telling that story in a fresh way every year.”

Adam&eve won the treasured John Lewis account in 2008 after Murphy and his team won plaudits for their work with M&S at rival firm RKCR/Y&R.

Murphy claims the success of the John Lewis adverts is the result of a collaborative effort with the retailer’s marketing team and they did not set out to establish a new standard for Christmas advertising campaigns.

However, working with John Lewis has given adam&eve a stellar reputation in the industry. In 2012, advertising group Omnicom bought the four-year-old company for a price rumoured to be in the region of £50m.

However, next year Murphy faces a more daunting marketing challenge than ensuring the high street has a prosperous Christmas. He will be attempting to keep Britain in the European Union.

Adam&eve has been hired by the Britain Stronger in Europe campaign to lead their advertising drive to keep the country in the EU in the forthcoming referendum.

Murphy, who is also chairman of the industry trade body, the Advertising Association, feels strongly about the topic.

“We do work for that campaign because we are wholeheartedly behind that campaign,” he said. “We are a business that grew 26% last year and over half that growth came from continental Europe. I think there are clearly benefits to businesses of staying in the EU, but also benefits to people in the country of staying in.

“The modern world is about acting together and alliances. It is ludicrous to believe we will be stronger and more prosperous going it alone.

“The thing that is most worrying about the discourse is that when you listen to the people who want out, they just want out, they have no idea about what out is. It is a strange group of people who want out. They are almost like the ‘new Victorians’. They have this idea of Britain ruling the waves gloriously.”

Murphy said the referendum will present “the biggest decision we will make in a generation”, meaning that adam&eve could prove to be a remarkably influential organisation in the next year.

However, with the company running the Stronger in campaign across social media and the web as well as traditional media such as television and newspapers, Murphy insists the modern advertising world is a long way from the glamour portrayed in Mad Men, the hit US television drama.

“I would say it is a more practical job and also a much more accountable job now,” he said. “You are juggling a lot of different priorities and technologies at the same time. We know when we create a campaign very quickly how it is working.”

Murphy was a van driver for a year after leaving university before deciding to begin a career in advertising because he was intrigued as to how it mixed creative and business minds.

“You probably have to be a bit more of an adrenalin junkie to work in the industry now,” he said. “When I started as a grad trainee, you were still allowed to smoke in the office, and there were guys with big corner offices who enjoyed long lunches. But that seems a world away.”