Sarah Grantham pointed out a great source for info on Friths in Derbyshire.

This site
http://homepages.rootsweb.ancestry.com/~spire/Yesterday/inde...
has extracts from Apprentice Records, Bastardy Papers, Board of Guardians, Cemetery Records, Coroner's Records, Law and Order, Red Tape, Removals, Rogues and Vagabonds, Settlement Certificates, Schools, Settlement Examinations, Wills and Administrations, Workhouse Registers

To search for people surnamed Frith, use the following (without the quotes) in google or similar search engines:
"frith site:http://homepages.rootsweb.ancestry.com/~spire/"

I get over 100 hits, going back to 1598 or earlier.

Richard Thrift

...there are also listings for Fryth, Frythe etc.

And for Firth, Fyrthe, etc, which are probably related in at least a few cases, going back to 1563 or earlier.

Richard