London talk show

On my many nursery runs I've started to listen to Robert Elms show on BBC London Radio. He's really interesting, you can find out some mad things about London. For example, I found out where the smallest ever police box was. Do you know where? Someone phoned in and told us avid listeners that on the south east corner of Trafalgar Square there used to be a police box which is now used for storage equipment. I find these little facts interesting - the fact that I have walked past there so many times and not known that it was used as a police box!
The other day people were phoning in to tell people about hidden tunnels under London. A cabbie (London Cab driver) called in to tell us listeners that there is apparently a secret tunnel running from Buckingham Palace to Windsor!! We'll never know if that's true but its interesting nevertheless ..