Complex sentence: The Royal Navy Sailor's Fund, a Navy charity, receives royalties from the proceeds of each bottle of the rum sold, and that is now the charity's largest source of income apart from the founder's original bequest.
Split into simpler sentences: The Royal Navy Sailor's Fund, a Navy charity, receives royalties from the proceeds of each bottle of the rum sold. Today, these proceeds are the charity's largest source of income, apart from the founder's original bequest.