The BBC's global ambitions must not damage the Corporation's distinctive Britishness

But to some degree the casting did feel like a bit of a stunt, a nod to audiences in the US where the highly talented Ullman is an even bigger star than she is in the UK (Howards End is a co-production with American network Starz and is billed as a Starz production in the US).

With changes afoot in the BBC, this kind of thing may occur more often. Not just in terms of co-productions with American broadcasters – that sort of thing is the norm these days – but in the way shows are made and feel.

Earlier this week the BBC revealed that, from April next year, it will merge the activities of its commercial arm BBC Worldwide and its production arm BBC Studios.

BBC Worldwide is tasked with promoting and selling the BBC's great British shows abroad. BBC Studios is responsible for actually making them.

As we suggested at the time, the move is a clear attempt to strengthen the BBC’s commercial clout, to streamline its activities and also to make sure that the BBC is able to raise extra revenues on the international market through secondary sales and merchandising.

BBC Studios as a commercial production company is also free to produce content for broadcasters other than the BBC, bringing the BBC in line with rivals such as ITV and All3Media, which have integrated their production and distribution businesses.

But does this commercial ambition mask a growing problem in the global TV market?

The BBC’s primary purpose is to serve licence fee payers; to educate, inform and entertain people in this country? The point of the BBC it seems to me is that it is a very British service, paid for by UK viewers to serve the UK market.

That means the very high standards we expect from BBC News, Countryfile, oh so British comedies like Detectorists and everything else we know and love. It doesn’t mean turning the BBC into a super indie serving the growing TV marketplace, and especially the one in America – the biggest marketplace of the lot.

To me the principal danger is that commissioning decisions made by BBC Studios could be led, consciously or not, by the commercially-minded BBC Worldwide. And if that's the case, future BBC dramas could be conceived, commissioned and produced with US rather than UK audiences in mind.

Peaky Blinders, which also airs exclusively on Netflix in the US, is an excellent drama with significant cult appeal in America. And of course, it’s great that a show about gangsters in 1920s Birmingham can attract big Hollywood stars like Adrien Brody in the current series.

But it’s worth noting that one of the things that gives so many BBC shows their value are their 'Britishness' – a tricky quality to define, but a clear selling point for international audiences.

The ex-Top Gear duo of James May, Jeremy Clarkson and Richard Hammond knew this. They attracted a global audience of around 350 million for Top Gear without making a single concession to their unique way of going about things.

Even after their high profile move to Amazon they were adamant that things wouldn't change. As producer Andy Wilman recently noted, the guys have been under “no pressure” to Americanise what they do to “suit the American market”. “They have never asked us to say trunk rather than boot,” he noted.

Ironically, it is the rise of US giants like Amazon and Netflix that the BBC is worried about, and which is motivating its mover towards greater commercialisation.

Last month Tony Hall warned about the “serious threat” posed by the emergence of the big US players like Apple, Amazon and Netflix which he said would lead to a drain on money spent on British TV productions

He cited a survey commission by the Corporation from Mediatique suggested that this could comprise a fall of around £500m a year over the next ten years.

So of course the BBC needs to engage with the reality of the changing TV marketplace and put its mind to the importance of generating revenue. Clearly something needs to be done, and if a British TV show gets wide appeal in America, if US frat parties continue to hold Peaky Blinders-themed events, it is not the worst thing in the world.

But the BBC needs to be cautious now that its production arm is so tightly bound up with Worldwide, a commercial operation that is already having an increasing say in creative as well as commercial decisions around key shows like Blue Planet II, Top Gear and Doctor Who.

Clearly the BBC is alive to the challenges of the modern TV marketplace. But it must be careful to ensure that the commercial arm does not lead the creative head.