Complex sentence: Cork Gully was a British insolvency practice, pre-eminent in its field between the 1960s to 1990s; it became part of PricewaterhouseCoopers, which stopped using the brand in 1999.
Split into simpler sentences: Cork Gully was a British insolvency practice, pre-eminent in its field from the 1960s to 1990s. It then became part of PricewaterhouseCoopers, which stopped using the brand in 1999.