Shane,

Your 'Oiseau' mark is a pattern name.  Unfortunately, it is not listed in
sources like Petra Williams books Staffordshire Romantic Transfer Patterns
or her Staffordshire II Romantic Transfer Patterns.  Your best bet for a
date might be to compare the pattern with the chronology developed by
Patricia Samford in her article "Response to a Market: Dating English
Underglaze Transfer-Printed Wares" that was published in Historical
Archaeology.  It has been reprinted in Approaches to Material Culture
Research for Historical Archaeologists edited by David R. Brauner and
published by the Society for Historical Archaeology.  For those not
familiar with this work, it contains 25 articles on ceramics, glass, metal,
and the interpretations of assemblages that have been reprinted from
Historical Archaeology.    It is available from the SHA for $25 plus
shipping.

Peace,
George L. Miller
URS Corporation
561 Cedar Lane
Florence, New Jersey 08518