Veteran broadcaster James Naughtie has apologised after referring to Caitlyn Jenner as "he" during a discussion on Radio 4's flagship Today programme.
The American celebrity formerly known as Bruce made her debut as a transgender woman called Caitlyn in Vanity Fair earlier this week.
In just four hours she had gained a million followers on Twitter as images of the front cover photoshoot by Annie Leibovitz - showing long-haired Jenner in a strapless corset, legs crossed, sitting on a stool - went viral.
Jenner has previously talked of preferring the use of "he" but tweeted: "'I'm so happy after such a long struggle to be living my true self. Welcome to the world Caitlyn. Can't wait for you to get to know her/me.''
During a discussion on Today, Naughtie said: "Now, this is complicated. He used to be called Bruce but he's now a woman. I realise some of you will never have heard of Kim Kardashian, let alone her stepfather, who was Bruce and is now a woman but, anyway, they are very well known on television."
He added: "There's not a million people going on because they are interested in discussing transgender issues, surely. They are on it because he/she is a celebrity."
Naughtie was criticised on Twitter for referring to Jenner as he.
Fat Jacques wrote: "Can someone explain to Jim Naughtie what mis-gendering is. He did it to Caitlyn Janner several times this morning."
Catherine tweeted "not heard reporting that bad about a trans person in a long time" while Deptford Dame wrote: "James Naughtie struggling a bit on BBC Radio 4 Today with his transgender references. Need to try harder than 'he/she' Jim!"
Naughtie later apologised, writing: "If Caitlyn Jenner wishes to be known as she, of course she's entitled to that, and I'm sorry for saying 'he' on air. A bit sloppy."