How long was Matthew Flinders imprisoned?

Answer:
Matthew Flinders was captured by the French on the island of Mauritius in 1803. He was kept prisoner until 1810 on the grounds that he was a spy. Therefore, he was imprisoned for about 7 years.
First answer by On the Wallaby. Last edit by On the Wallaby. Contributor trust: 2771 [recommend contributor recommended]. Question popularity: 9 [recommend question].