Hopefully someone can clear this up for me!

I'd read (in one of those very old Retro Gamer issues) about the Dizzy series, and an interview with the Oliver Twins mentioned that the last game the twins worked on was Fantasy World Dizzy.

I'm a little confused with them being the writers of Fantastic Dizzy, as I always assumed they'd left the series behind at Dizzy's third game? Could someone please clarify the Oliver Twins' input on this title, and where this was stated?

Thanks!