In February of this year, Netflix won its first Oscar and its first Bafta. Surprisingly, the awards were not for any of its high-profile drama series, but for two documentaries. The Academy Award went to The White Helmets, a film about a group of Syria Civil Defence volunteer rescue workers. The Bafta winner was 13th, Ava DuVernay’s film about race in the US criminal justice system.

The two prizes have highlighted the growing part that documentaries are playing in the Netflix portfolio and the impact that is having on the world of factual television. “UK producers are queuing up to have a conversation with them,” says Greg Sanderson, Managing Director of Brook Lapping.

Listing “the 28 best documentaries on Netflix”, Time Out wrote recently: “Netflix has revitalised the documentary industry. Making a Murderer became a global talking point overnight, followed by exclusives such as 13th, Amanda Knox and The Ivory Game, while the streaming site’s archive of great documentaries has proven enormously popular.”

Meanwhile, Amazon Prime used last autumn’s launch of The Grand Tour, with Jeremy Clarkson, Richard Hammond and James May, as a huge marketing campaign to woo new subscribers. It is following up with a new portfolio of unscripted series, including two that venture behind the scenes in motor sports.

So how significant is the streaming behemoths’ growing focus on factual television, and what does it mean for UK producers and broadcasters?

Steve Anderson, former head of news and current affairs at ITV, knows the US market well. He set up the international division of NBC’s Peacock Productions. He says cautiously: “There’s been some investment in factual so far, but not a lot – certainly, in comparison with drama. I don’t think they have fully worked out their strategy. But the signs are that it will get stronger, and that is good news for UK producers.”

John Battsek of Passion Pictures produced the latest Netflix documentary series, Five Came Back, which examines Hollywood and the Second World War through the eyes of five legendary directors who went to film in combat zones – including John Ford and William Wyler.

Battsek is a double Oscar winner, who has worked with HBO, the BBC, NBCUniversal and A+E Networks. He is full of praise for Netflix.

“Its documentary team is superb and has the ability to access good-sized budgets to enable us to make big, cinematic, broad-reaching films,” he says. “It also has the muscle to promote them powerfully and enable them to reach really big audiences.”

Five Came Back exemplifies Netflix’s ambitious approach. Narrated by Meryl Streep, the five-part series features interviews with Steven Spielberg, Francis Ford Coppola, Paul Greengrass and other directors, talking about how earlier film-makers helped show America the realities of war.

Netflix has also added 13 film documentaries discussed in the series to its archive catalogue, including Ford’s The Battle of Midway and Wyler’s The Memphis Belle: A Story of a Flying Fortress.

This is Battsek’s second production for Netflix, following Winter on Fire: Ukraine’s Fight for Freedom.

Passion Pictures is also about to make its first two documentaries for Amazon. “It’s really exciting to have two such big, aggressive players as part of the documentary community,” he says. “From a producer’s perspective, the more people with the muscle to finance the big docs we make, and the know-how to exploit and release them, the better.”

Established documentary broadcasters are feeling the heat, believes Sanderson, who worked with many partners worldwide as executive editor of the BBC’s Storyville strand. He says: “I was in the US the other week and saw HBO and PBS and a few others and they are suddenly feeling that they’re not the biggest boys in town. They used to be able to go to Sundance and other festivals and buy the docs they wanted and that’s not now the case – they can be blown out of the water.”

But it is still early days, as Conrad Riggs, head of unscripted for Amazon Originals, acknowledges. “We have a saying at Amazon, it is ‘Day One’ – our main building in Seattle is even called Day One,” he told an audience at the recent MIP Formats market. “We’re just starting – but we believe that we have an opportunity to bring great factual content to our customers.”

Riggs says the show that he is most proud of is All or Nothing, a series about American football, and Amazon’s first sports Emmy nomination. The cameras followed the Arizona Cardinals throughout the 2015 NFL season.

ShortList, the UK men’s magazine, wrote: “An absolute game-changer of a series. It’s reality TV for sports fans and is a fascinating insight into the major personalities and their experiences.”

Riggs has just announced the show’s second season, focusing on another NFL team, All or Nothing: A Season with the Los Angeles Rams.

On similar lines, he has green-lit a series following McLaren Racing as it competes in the 2017 Formula One World Championship, and another about the Le Mans endurance race – Le Mans: Racing is Everything, produced by the UK company New Black Films.

“These are all opportunities to get inside worlds that people don’t know the details about,” says Riggs. “Viewers get really deep, intimate access and exciting storytelling, and an honest look at extraordinary people doing extraordinary things.”

Amazon has also commissioned Lore, a series about supernatural and real-life horror stories, based on a popular podcast.

Riggs says that he will take ideas from anywhere, and any part of the world: “I like to be open to anything. You never know where the next great idea is going to come from. We’re trying to make a statement and do things differently and take risks.”

An obvious attraction for programme-makers is that Amazon and Netflix pay big money. But Anderson points out that they also demand to see that on the screen, as with The Grand Tour and The Crown. For the latter, “Netflix paid a well-publicised £100m for 20 shows but you see that £100m on the screen. Thirty thousand pounds for Claire Foy’s dress? I know people making documentaries for less than that on BBC Four.”

The streaming and subscription model has another benefit, he says: “You escape the tyranny of the slot and the fixed time-length. They don’t have the mainstream broadcasters’ problems of trying to attract audiences to attract advertising money.

“Having got their subscribers in, they want to give them a wide range of programmes to enjoy.”

Sanderson agrees: “When you talk to Netflix, it is not prescriptive about length or slots or any of the traditional boundaries that we’ve had.

“Making a Murderer was in 10 parts. I don’t think that it would have worked if you’d tried to condense it into three or four, because it’s the detail that drags people in.

“It is amazingly liberating, but, for people who’ve grown up in the industry here, it takes a bit of getting your head around.”

The huge success of Making a Murderer also led Netflix to say it needed more crime, says Anderson. “After I left Peacock, they got a call from Netflix asking if they had any good crime series for it – and it just so happened that they did.

“The other day, I found out that it has bought a series I made six years ago, for Mentorn, called The Murder Files – the producer suddenly started getting emails from people in the US about it.”

But it is the big original series that define Netflix and Amazon, and they don’t come bigger than Our Planet. The eight-part Netflix series is being filmed over four years using 4K Ultra-HD technology by the team behind Planet Earth, Alastair Fothergill’s Silverback Films.

It is scheduled for screening in 2019. In the past, such blockbuster series would have been international co-productions – usually involving the BBC – but this one, like The Crown, has been funded by Netflix alone.

Sanderson says the streaming giants are rewriting the co-production rules. “They want global rights, they don’t want any partners. They don’t want any geo-blocking. In the long term, I don’t think that’s great for broadcasters such as the BBC or Channel 4.”