I've been discussing this topic with someone via PM and I thought maybe others could add some names to the list.
Here's what I know of so far:
Melanie Jeschke's Oxford Chronicles
Lori Wick's English Garden series
Lawana Blackwell's Gresham series
Penny Culliford's Theodora series and other books
anything by CS Lewis obviously
Elizabeth Goudge's books certainly have Christian themes although not as obvious in her fiction as in her non-fiction
Jan Karon's new Father Tim book is supposed to be set in Ireland, the new Sisterchicks book is set in England
Melody Carlson has a book set in Ireland
Liz Curtis Higgs Scottish series
Kathleen Morgan has a historical series
Sandy Dengler's ancient history series
some of Gilbert Morris although not all
Catherine Palmer's English Ivy series
The Heathersleigh Hall series by Michael Philips
the Eden Hall series by Veronica Heley
Julie Klassen Lady of Milkweed Manor
Legend of the Emerald Rose by Linda Wichman ? Not sure, never read this title
Ruth Axtell Morren has several regency era england
Bodie and Brock Thoene Ireland ?
Linda Windsor Ireland?
Last Edited on: 7/10/08 4:22 PM ET - Total times edited: 1
Off hand I thought of the Wakefield Dynasty by Gilbert Morris.
Also one of my favorite authors from the UK is Stephen Lawhead. I believe he is a Christian and writes with a Christian bent, but not sure if he is considered primarily a Christian author. Several of his novels are historical taking place in Ireland, England, Wales, etc.