That's a very good question which goes unanswered in the reports.
The closest it comes is "Mrs Fergus had said she was haunted by some of the imagery in the film..."
I imagine she's torturing herself by watching trailers and clips like this: https://www.youtube.com/watch?v=w7dOW8Zj-_w
It's very likely to go largely unseen.
"If Lambe’s plan had been to boost his own prospects with the pre-release controversy, it has backfired. He’s also found himself in a slightly Kafkaesque situation whereby he can’t defend his film’s balanced perspective by showing it to the British public. “The trickiest place to get it shown is the UK, and that’s the most important place for it to be shown.
“I don’t know if a TV station is going to take it. It’s kind of hard to get them to do it when people are saying it shouldn’t have been made and you shouldn’t watch it.”
The contract he’s signed with his distributor means he can’t post Detainment for free online and his approaches to cinemas have met with silence. “We said the proceeds would go to the James Bulger Memorial Trust if they did want to show it but no one wants to screen it so far.”"
via: https://www.standard.co.uk/go/london/film/detainment-director-vincent-lambe-james-bulger-case-a4041341.html
(, Sat 26 Jan 2019, 22:33, Reply)