Unused FM radio frequecny in London

[Donner Kebab]

I have an I Trip for my I Pod but for the life of me cannot find a clear enough radio frequency in London (W1 Area)  to get a clear enough sound out of the radio. It works at home and in the car just not in central London, has anyone found an empty frequency or one that can receive the signal from the I Pod in the W1 area? Thank you!

[SpyWriter]

I have the version that plugs into cigarette lighter. Doesn't matter about free frequency (I sometimes pick up a distant station when iPod is off) the signal is stronger than the radio signal.