Complex sentence: The old St. Ives was originally in the valley at Harden and the Estate we now know as St. Ives was originally known as Halton Grange then as Harden Grange, but in the 19th Century the two names Harden Grange and St. Ives were interchanged.
Split into simpler sentences: The old St. Ives was originally in the valley at Harden and the Estate we now know as St. Ives was originally known as Halton Grange then as Harden Grange. In the 19th Century however, the two names Harden Grange and St. Ives were interchanged.