Radio and TV personality Neil 'Dr' Fox has been arrested on suspicion of sexual assault.
The veteran DJ was held on suspicion of assaulting two women, soon after he finished presenting 105.4 Magic FM.
The former Pop Idol judge was taken to a central police station to be questioned. He currently remains in police custody.
Officers searched addresses in Chelsea, west London, and Littlehampton, West Sussex, as part of the investigation.
Fox has not been arrested as part of Operation Yewtree, the Met Police inquiry investigating sex offence allegations set up in the wake of the Jimmy Savile scandal.
A Met Police spokesperson said: "Officers from Westminster have this morning, Tuesday, 30 September, arrested a 53-year-old man following allegations of historic sexual assault against two women.
"The man remains in custody at a central London police station."
"On 30 September, officers searched an address in SW6 and in the Liittlehampton area of West Sussex. The man was arrested at a business address in W1."
Bauer Media, who own Magic FM, said Fox will not be presenting the next morning breakfast show following his arrest.
A spokesperson added: "In the circumstances Neil will be off air from tomorrow to enable him to devote his full attention to dealing with these matters. All other aspects of his contract will remain unchanged while matters are resolved. We can make no further comment at this stage."
The former Capital FM DJ has been a breakfast presenter on 105.4 Magic FM since 2005.