To find out more about the Blue Badge seal of approval and the profession:

Association of Professional Tourist Guides www.aptg.org.uk
Guild of Registered Tourist Guides www.blue-badge-guides.com
Institute of Tourist Guides www.itg.org.uk

To find out about some of London's sites and museums:

Westminster Abbey www.westminster-abbey.org
Tower of London www.hrp.org.uk
St Paul's Cathedral www.stpauls.co.uk
British Museum www.britishmuseum.org
National Gallery www.nationalgallery.org.uk
City of London www.cityoflondon.gov.uk
Museum of London www.museumoflondon.org.uk
Hampton Court www.hrp.org.uk

To find out about another good guiding organisation:

Keith Bates www.londonbluebadgeguide.me