Yes I am using the windows .exe version of Exiftool. Could it be that my version of Windows is set to UK daylight savings settings and maybe Pearl is using US?
I have tried to bring back the filemodifydate by one hour as suggested by no joy. Perhaps I'm doing something wrong?
D:\Photos>exiftool -alldates -fileModifyDate -s -G1 D:\Photos\Library\2006\03\26
\*
======== D:\Photos\Library\2006\03\26\2006-03-26_D50_DSC_0549.JPG
[ExifIFD] DateTimeOriginal : 2006:03:26 10:31:13
[ExifIFD] CreateDate : 2006:03:26 10:31:13
[IFD0] ModifyDate : 2006:03:26 10:31:13
[File] FileModifyDate : 2006:03:26 11:31:13
14 image files read
D:\Photos>exiftool "-fileModifyDate-=1" D:\Photos\Library\2006\03\26\* -r -ov
erwrite_original
0 image files updated
14 image files unchanged
D:\Photos>exiftool -alldates -fileModifyDate -s -G1 D:\Photos\Library\2006\03\26
\*
======== D:\Photos\Library\2006\03\26\2006-03-26_D50_DSC_0549.JPG
[ExifIFD] DateTimeOriginal : 2006:03:26 10:31:13
[ExifIFD] CreateDate : 2006:03:26 10:31:13
[IFD0] ModifyDate : 2006:03:26 10:31:13
[File] FileModifyDate : 2006:03:26 11:31:13
14 image files read
Justin..