Museums & Galleries with large collections of portraits and/or miniatures

• National Portrait Gallery, London
  
• The Scottish National Portrait Gallery, Edinburgh
• National Gallery of Ireland, Dublin
  
• Victoria & Albert Museum, London
  
• The Royal Collection, London
  
• The Wallace Collection, London
• Compton Verney, Warwickshire (significant collections of British portraits & British folkart)
  
• The Fitzwilliam Museum, Cambridge
• The Holburne Museum of Art, Bath
• The Ashmolean Museum, Oxford
• The National Trust properties
• Malahide Castle, Dublin (silhouettes)

Other Personal Favourites well worth visiting

• Geffrye Museum, London (focuses on historical English interiors)
  
• Sir John Soane's Museum, London (a treasure-trove of antiquities and works of art)
  
• The Bowes Museum, Barnard Castle

Antique Shopping

• Woman's Work, old toys, needlework pictures
• Mackay & Field Antiques, American country antiques
  
• Christine Gardner Antiques, early American folkart
• Antiques for Everyone fairs
• The Harrogate Antique & Fine Art Fair

Other Recommended websites

• Phyllis A Arnold RMS, to commission a portrait miniature or silhouette
• The Costume Gallery
  
• Cultural Property Advice, advisory service for buying & selling antiques in the UK
• The National Archives