Complex sentence: Whinfell Forest was originally built and operated by the Rank Organisation, as the sole competition to Center Parcs in the UK, however, after a short period of a few years, Oasis, as Rank had named it, was sold to Center Parcs.
Split into simpler sentences: Whinfell Forest was originally built and operated by The Rank Organisation, as the sole competition to Center Parcs in the UK. However, after a short period of a few years, Oasis, as Rank had named it, was sold to Center Parcs.