Complex sentence: The three-manual organ, with its baroque case, stands on the street-facing side of the gallery; it was built in 1864 by the Manchester organ builders Kirtland & Jardine.
Split into simpler sentences: The three-manual organ, with its, stands on the street-facing side of the gallery. The baroque case housed an instrument built in 1864 by the Manchester organ builders Kirtland & Jardine.