I don't subscribe to findmypast, but I am registered with them so often look at their records. This is how it was described to me, hope it helps.

When searching for a person on findmypast it doesn't check for individual names it says if a person of that name is in the index then this is the page it would be on. You have to then look at the page to see if the person you want is actually on it similar to a telephone book. Looking for example for Alice Cowdry the page starts with Alice Cowdrey and finishes with William Cox in other words a list of names of people who alphabetically fall between Cowdrey and Cox.