Complex sentence: The company claims a continuous heritage since the 1807 creation of the Bibby Line by the first John Bibby (1775-1840), but in fact the Bibbys were not in the shipping business for some years after 1873.
Split into simpler sentences: The company claims a continuous heritage since the 1807 creation of the Bibby Line by the first John Bibby (1775-1840). However, the Bibbys were not in the shipping business for some years after 1873.