Hi Barbara I have a great deal of Duckenfield information for Yorkshire (as I live there!). I know that I have birth information on Duckenfield births with the Mother's Maiden name of Firth. In fact, I have a database of all the Duckenfield (and Duckinfield) births from 1837 to 1950 extracted from the Registration Index. I'm currently extracting all the deaths, and will then start on the marriages. The births will be searchable on the Guild of One Name Studies website in the near future. In the meantime, email me and I'll run a lookup.
Also, just to let you know that we have a Duckenfield message board and mailing list on Rootsweb.com for the Duckenfield surname. You are certainly welcome to join us.