The show is in full swing when I arrive at the Leicester Square studios of 95.8 Capital FM to watch the final hour of Johnny Vaughan's fourth day in his new job.
A phone-in on listeners' embarrassing crushes has taken on a life of its own and Vaughan and his sidekick, Becky Jago, are wading through hundreds of text messages divulging secret longings for candidates such as William Hague and Judith Chalmers.
The atmosphere in the studio is relaxed but busy. And despite being only four days into his job, Vaughan has gelled with them all, including Jago, who often cuts him short on-air and doesn't always laugh at his jokes.
Off-air, they discuss ideas and pore over the hundreds of texts that have been sent in.
Vaughan's relief at the phone-in's popularity is evident when he jokes that he might let it run and run. Otherwise, he appears relaxed, chirpy and unfazed by the pressure of being at the controls of London's biggest radio show.
The scale of his task cannot be underestimated. Vaughan has landed the most important job at Capital. He is replacing Chris Tarrant, who, after 17 years, was still waking up a peak audience of 1.8 million listeners when he quit.
Mike Buckley, the radio direc-tor at Capital's media agency, ZenithOptimedia, thinks Vaughan fits with Capital's aim of targeting 25- to 34-year-olds, while retaining its wider reach of 18- to 44-year-olds and that there is every chance the show will work.
"Other broadcasters are seeing this as an opportunity to grab listeners from Capital, but it's also an opportunity for the station," Buckley says.
Vaughan's arrival has allowed the station to tweak the breakfast format.
Jago has more prominence, helping to compete with Heart FM's position as a softer alternative to Kiss FM's laddish Bam Bam show. The show also seems more London-focused, backed by its ad campaign, which aims to inspire loyalty from its audience.
Another difference from Tarrant's show is that Vaughan involves his team more, which makes up for the feeling that he has yet to develop the presence of his predecessor.
Music runs throughout, but the show's focus is chat and humour, although this needs polish. Some of the jokes and features are a bit forced, particularly a lottery-style game called Becky's Balls during the first hour. Later on, he is more spontaneous, proving he still has the comic timing that made his name on The Big Breakfast.
With 15 minutes to go until the end of his three-hour stint, Vaughan rubs his eyes with clenched fists, a sign that he is feeling the strain.
There are plenty of challenges ahead of Vaughan (he has yet to do a big-money promotion, a Tarrant speciality). Buckley thinks many people will want to try Vaughan out, but that it will be down to the format and music content to get them to come back.
Capital must expect to lose some listeners, because Tarrant was unique in appealing to such a wide age range, but if Vaughan manages not to alienate any section of the audience, the damage to ratings could be limited.