BritBox, the U.S. streaming service operated by British commercial broadcaster ITV and BBC Studios, has added 150,000 subscribers in the last six months, taking its total to 400,000.

Chief Executive Tim Davie, speaking at the IBC technology conference in Amsterdam, added that he has set a target of 500,000 subscribers by March 2019.

“We haven’t gone public with a number but why don’t I, we’re over 400,000 now within 18 months. By its second birthday, I’m looking for half a million, that’s quite a lot of candles on the cake We’re doing well,” he said.

BritBox is now competing with the likes of Netflix, Amazon and Hulu as well as UK-focused rival Acorn TV and Davie said that it was a big niche with plenty of opportunity and was now making “tens of millions of dollars”.

“We’re not trying to beat Netflix in that market, I think that might not work but what we are doing. We saw an opportunity where there are a lot of people, not just expats, that would like a deeper [service]. It’s gravy,” he said. “You have to be humble about the US and these big markets because it can be very difficult to arrive and say ‘I’m here’ but if you can get those big niches right, it’s big money.”

In addition to over 4,600 episodes of British programming, the service has also moved into original commissioning with series including The Bletchley Circle: San Francisco from Line of Duty producer World Productions and Canadian firm Omnifilm Entertainment.

“Everything is about [making] talent happy and they need to see their projects happening,” he added.

Davie added that it was “evaluating” the launch of BritBox in a number of other international markets.