The search rules are roughly

Take the supplied search string and
Strip out ' characters
Split everything into words
Throw away duplicate words
Ignore the, a, an, etc.
Match all words against dance (author, book, recording) names in the database
As a special case any word ending 's is stored in the index as both the word with and without the possessive s on the end. (Hence a search on Walpole will find both Walpole Cottage and Lady Walpole's Reel.)
If you get a full match then that's the winner
Otherwise report all dances (authors, ...) that match, sorting the results by the number of matching words

This means that a search for (the nonexistent) Lady Godiva's Reel will find Lady Walpole's Reel and reels belonging to various other ladies, followed by a mass of dances with titles containing one of the words Lady or Reel. Were a there dance called Godiva's Gallop then it would be found, but buried in amongst all the other single-word-match results. (Maybe I should do something clever to push more selective words up the results table.)

For added cunning, the word matching is actually done using Soundex - this is an algorithm cooked up a hundred years ago, where a word is basically mapped to the initial letter followed by just its consonants, with consonants batched into half-a-dozen similar-sounding groups (so B and V map to the same, as do D and T) hence mapping both Playford and Plaifurt to P4163 (or, more usefully, both MacGregor and McGregor to M2626). (See Knuth 3 Sorting and Searching if you are desperate.)