The second series of The Masked Singer is well under way on ITV in the UK and it's proving a perfect piece of entertainment to distract us all from the coronavirus pandemic.

It features 12 contestants who conceal their identities inside an elaborate costume as they perform in front of a panel of four judges.

Episode 1 of the second series went out on Boxing Day 2020, with American comedian and actor Ken Jeong unable to return to the panel because of Covid-19 travel restrictions. He was replaced by comedian Mo Gilligan.

The other panellists are Jonathan Ross, Rita Ora and Davina McCall. Guest judges sometimes appear too - in the first series, Donny Osmond, Sharon Osbourne and her daughter Kelly Osbourne filled in for Jeong when he couldn't make it.

The second series has seen Alan Carr coming on the show as a guest panellist.

Stars unmasked so far include Sophie Ellis-Bextor, Mel B, Martine McCutcheon, Glen Hoddle and John Thomson, along with a-ha frontman Morten Horket and Lenny Henry.

So how does it all work? Here we look at the secrets of the show.

When and where is it filmed?

You may be amazed to learn that The Masked Singer was recorded back in September 2020. That explains why there are no phone-in votes or other live interactions with viewers at home.

Showbiz magazine Variety published an article on October 11, 2020, that said the second series had wrapped filming and was in post-production.

According to The Daily Express, filming took place over eight nights, starting on Monday, September 14 .

Government guidelines at the time enabled it to go ahead with a live audience in socially-distant bubbles, plus perspex screens between the panellists.

The security duo who walk the performers to and from the stage are in face coverings, and host Joel Dommett can no longer hug the singers but has to stand two metres apart at all times.

Filming takes place at ITV Studios Bovingdon, a former RAF airfield site in Hemel Hempstead, Hertfordshire, just over 20 miles outside London.

What are the rules for the audience?

In a special show going behind the scenes and catching up on all the celebrities unmasked in the first series, it was revealed that audience members have to sign non-disclosure agreements and hand over their mobile phones before going into the studio.

But you may be astonished to learn that they also don't get to see the identity of the star inside the costume. That was true in the first series at least, as Joel Dommett explained.

Joel previously said that the audience, who join in the chants of "take it off", were asked to leave the studio when the unmasking takes place.

He said on Sunday Brunch during the first series last year: "We record the whole show and then they get to the bit where they go 'take it off, take it off', they go to take off the mask and that's the point where, I don't know if I'm allowed to announce this, we then get rid of the audience so they can then keep it a secret."

"The entire audience leaves, and they're very angry about that. And after we get rid of the audience, we reveal who it is."

This would mean that audience members themselves can't spoil any of the big reveals before the show goes out on air.

But they still have to sign non-disclosure agreements so they can't talk about the costumes, the songs, the panel's guesses or any rumours of the star's identities they hear floating around in the studio.

How else are the performers' identities kept secret?

Panel member Mo Gilligan recently revealed the extreme lengths the show goes to in order to keep everyone's identity hidden, WalesOnline reports.

Speaking to Alison Hammond on her My Life In TV podcast, Mo said: "The set is huge. I got in the car, the driver was instructed he can't talk to me. I cannot talk to you, I'm not allowed. There's a gate. There's another gate with huge security guards. This happened every single day."

He added: "You don't see anyone, you go straight into your dressing room, it's so secretive. It's a fun show, it's a really good family game."

Glen Hoddle, who was unmasked as the person inside the Grandfather Clock outfit, showed in a Twitter picture how he had to wear wore an all-black outfit with gloves, a face shield and a sweatshirt with Don’t Speak To Me emblazoned on the front.

And there were further revelations from Sophie Ellis-Bextor who was first to be unmasked in the second series after her performance as the character Alien.

She confessed that she knew she had been sussed out after three of the judges came up with her name - but all that was edited out, making it more mysterious for viewers at home.

She told The Sun: "They didn't put it in the edit but three of the judges said my name, so I already knew so I'd been rumbled."

None of the judges stuck with her name as their final answer, with Lily Allen, Anna Cooper, Sophie Dahl and Brenda Blethyn instead being the guesses we heard broadcast just before the unmasking.

However, Sophie's distinctive voice was instantly recognised by many people.

She had only told her family she was going into London for work and had tried to disguise her vocals while singing Dua Lipa's Dont Start Now - but even her one-year-old son Mickey guessed it was her.

Following her elimination, Sophie shared a selfie on Instagram as she posed next to her Alien mask and admitted her children were not fooled for a second, the Daily Mail reported.

She wrote: "Even my one-year-old pointed at the telly and shouted "mummy!" when I started singing in the alien suit!

"Anyhoo a fun and trippy way to spend a few days and enjoy the rest of the show - no idea who anyone is!"

Sophie added that her other four kids - Sonny, 16, Kit, 11, Ray, eight, and Jesse, five - wondered why she had even tried to change her voice on the show.

She said: "My kids found it absolutely hilarious that I put on such a weird accent, they were like 'why on earth did you do that?'

"You want to have a recognisable voice if you're a singer but I felt like I'd done quite a good job so I was quite surprised."

Two vocal coaches work with each performer to try to change the way they sing but say they sometimes get them to put in a bit of their real voice as a clue.