You mention your branch of Percivals comes from Kent. I am descended from a John Percival who we believe was born in Seven Oaks, Kent on or about 22 May, 1835. He came to Australia as a ship's cook and then jumped ship. He married Clara Jane Lance in Braidwood, NSW in 1862. We believe he had been orphaned prior to coming to Australia but know next to nothing about his family in the UK. We know that he did visit relatives in Kent from time to time however.
My aunt has been researching this branch of the family for some years but seems to have little more than this although I don't know the latest update.
If you or anyone out there thinks they know anything about this branch of Percival's that would be wonderful.
By the way, I can't seem to access the website you mention.