For the past 50 years, Shell have been a dominant force in the North Sea.

As one of the largest oil and gas operators, it's presence has been a prominent one in the sector, although it has attracted it's fair share of criticism over the last five decades.

It all began for Shell on the Leman platform in the southern North Sea 50 years ago today.

Now Shell produces around ten per cent of the UK's oil and gas.

The Shearwater platform, which Shell calls it's jewel in the crown of the Central North Sea, produces 135,000 barrels a day alongside other platforms.

Now 20 years old, it remains a vital hub for the company

"We are investing heavily in this area to extend the life of this plant, this facility for many many years to come," explains Steve Phimister, Shell UK Vice-President UK and Ireland.

"The whole idea of that is to maximise the use of these hubs and these production facilities for the long term."

The huge Brent field east of Shetland became one of Shell's biggest assets.

But life in the North Sea has also brought tragedy. The 1986 Chinook disaster was one of a number of major helicopter crashes which cost lives in the field, killing 43 workers and two crew members who had been returning to Sumburgh airport.

Producing oil and gas remains a challenge, with the oil industry's peak days behind it.

Despite the tumbling prices of oil over the past few years, Shell remains a major producer.

"They are one of the silver threads or even golden threads which run through the whole North Sea story," explains energy analyst Jeremy Cresswell.

"They have longevity, they have track record, they've had their successes, they've had their failures but at the same time everybody has those.

"Shell wouldn't be here today if it didn't think the North Sea was worthwhile."

Yet Shell's growth has not always been welcome.

In the 1990s plans to decommission the Brent Spar storage installation and dispose of it in the North Sea brought it worldwide attention.

Shell's health and safety record has been cause for concern in the North Sea.

In the last ten years, it has been warned almost 50 times by the Health and Safety Executive for safety and pollution breaches.

In 2005 Shell was fined £900,000 following the deaths of two workers on Brent Bravo and in 2008 it was fined £150,000 after the death of a worker in the Southern North Sea.

Following an explosion at its gas plant in Norfolk, Shell was ordered to pay out over a million pounds in 2011.

Four years later it was fined for spills from Bravo and its Gannet Alpha platforms - and in January this year for a gas leak on Bravo.

Just two weeks ago Shell was fined £60,000 after a worker was badly injured on Brent Delta in 2014.

"Obviously things do still happen things that maybe shouldn't be happening," Mr Phimister adds.

"What's most important for the industry is that we learn from it quickly move on, improve it and invest to prevent any such repetition again."

Decommissioning the Brent field is now one of the biggest challenges Shell faces.

Yet the company is also trying to adapt to a new future.

Mary Church from Friends of the Earth believes that Shell should mark their anniversary by moving towards a future in renewable energy.

"Our birthday message to Shell would be that it's time to take action, to look at the consequences of its business model over the last 50 years and make decisions in the next two years and put them into action in the next ten years, to rapidly move away from fossil fuels and change towards a clean renewable energy future," she says.

"It needs to do so in a way which is fair to workers and the communities currently dependent on the jobs, we would urge them to work towards a just transition away from fossil fuels towards a low carbon economy."

"We fully expect to be a major energy company in the future, but the shape and form of the energy we provide is likely to change," says Sinead Lynch, Shell UK Country Chair.

"What that mix will be in the future we don't know now."