From a atheist's touristing point of view, Catholic Churches have many benefits as destinations. They never underwent the iconoclasm that protestant churches did, and the Catholic Church has maintained it's immense wealth so they'er still free to enter.
Owing to its size and position, the Oratory has played host to a few famous occasions over the years including the marriages of Edward Elgar and Alfred Hitchcock (not to each other).
For more information, visit the Oratory's website at http://www.bromptonoratory.com/
Click here to see the location on a map.