Complex sentence: During the winter of 1895-96 he made his own version of design by Léon Bollée he had seen in Paris, but he later found out that another British group had bought the rights so he had to come up with a design of his own.
Split into simpler sentences: During the winter of 1895-96 he made his own version of a design by Léon Bollée that he had seen in Paris. Later he found that another British group had bought the rights so Austin had to come up with a design of his own.