Barry Humphries has joked the reason 'Downton Abbey' is so successful in America is because of its all-white cast.

Barry Humphries as Dame Edna Everage

Barry Humphries as Dame Edna Everage

The 81-year-old star - made famous for his popular TV drag act Dame Edna Everage - has quipped that viewers in the US are drawn to the ITV melodrama, which came to an end over the festive season following five years on screen, because there are no black actors starring in it.

Asked why he thinks the period drama is so popular in the States, he told the RadioTimes magazine with a giggle: "Because there are no black people in it."

Nevertheless, 'Downton Abbey' had proved highly popular, both in the US and the UK, especially during the final episode on Christmas Day, which sent social media into overdrive, when it pulled in a jaw-dropping 10.9 million viewers.

And, although the doors to the Yorkshire country estate may now be closed for good, the success of the show continues as 'Downton Abbey' will go head-to-head with 'Doctor Who,' 'Casualty' and 'Broadchurch' for Best Drama at the National Television Awards (NTAs) later this month at London's O2.

The ceremony, hosted by Dermot O'Leary, will take place on January 20 at 7:30pm and will broadcast live on ITV.