It’s in the foyer of MACUSA, right above the staircase. An enormous, heavy and majestic-looking device with four faces and spindly black hands like the ones that patrol a clock face. It is unmistakably magical.

You may have spotted it, for a moment, in the Fantastic Beasts trailer, just to the right of President Seraphina Picquery’s portrait and above the team of Aurors running towards the stairs. It’s one of the most intricate props made for Fantastic Beasts and we’re going to tell you what it can do.

This device works like a barometer; like a meteorological instrument that could predict a change in weather. Only, it’s far grander than that. It’s more ominous. It measures danger...

This device measures the magical exposure threat level, or the risk of wizards and witches being exposed to the No-Maj community living in the United States of America.

The little hands swing between levels to indicate the level of threat – green for a low level threat, blue for high, yellow for danger, orange for severe unexplained activity, red for emergency. It counts the number of witch hunts in America, the number of times a witch or wizard has been exposed and the number of times someone has had to Obliviate a No-Maj.

If the magical community is vulnerable to exposure, or a No-Maj is at risk of witnessing magic, then this device will sound the alarm. It’s incredibly helpful to the Aurors in America.

‘There’s a miniature version of it on Graves’s desk,’ graphic designer Miraphora Mina says, conspiratorially. ‘He has his own,’ she tells me. Mira and her graphic design partner Eduardo Lima sketched this particular object in collaboration with production designer Stuart Craig.

‘Stuart was very clear about what he wanted,’ Eduardo says. ‘He wanted it to look like a station clock. We looked at how they show terror alerts in the States, and National Security issues like that, and used their colour scheme.’

‘It does say in J.K. Rowling’s script that there is a radar-type clock that’s measuring the amount of threat or danger,’ says Mira. ‘She says the dial is on “severe unexplained activity” and we came up with the other words on the clock face and the cogs you can see working underneath.’

‘Yes, an innocent little picture of ours is how that device started,’ says Eduardo. ‘From there an art director would draw up the technical spec to have it made and the props department would actually make it to that scale.’