AceShowbiz - Seal was so determined to keep his involvement in U.S. reality show "The Masked Singer" a secret that he even kept it from his own children.

The 56-year-old singer was unveiled as the Leopard on the semi-final of the programme on Wednesday night, December 11. And after the show aired, showrunner Izzie Pick Ibarra revealed that even the "Kiss From a Rose" singer's nearest and dearest, including kids Helene, Johan, Lou and Henry, were unaware of his appearance on the series.

"Leopard wanted to do the show because he wanted to surprise his kids. They still didn't know that he was on when the episode reveal aired," she told Variety.

"He did the whole thing to surprise his kids and make them laugh. I really wanted to send a camera, the moment that his kids see that it's him, but we couldn't, unfortunately, for various reasons."

The executive producer added that because of the fact children often struggle to keep secrets, show bosses always encourage contestants not to tell any youngsters about their involvement in the show.

"We encourage them to not tell as many people as they can," she explained. "We tell them not to tell their kids a lot because it's hard for kids to keep secrets, and it's not really fair of them, obviously - when you are seven or eight years old, you don't necessarily understand not telling people something."

As well as Seal's unveiling, Wednesday night's episode also saw The Thingamajig unmasked as NBA player Victor Oladipo.