Complex sentence: The locos were originally painted brown with gold and black lining, after the grouping replaced by crimson lake with gold and black lining and latterly after the Great Depression had set in with plain black.
Split into simpler sentences: The locos were originally painted brown with gold and black lining, after the grouping replaced by crimson lake with gold and black lining. Latterly, after the Great Depression had set in, they ran in plain black.