Jesson was a republican who championed an independent political and intellectual culture in New Zealand. He rebelled against the habit of the New Zealand Left to take its political cues from overseas countries. He founded the anti-royal Republican Association in 1966, later moving to Auckland (first to Pokeno, later Otahuhu and finally Mangere) and forming a political party (the original Republican Party) to push the republic issue in 1967. Around 1970 he also associated briefly with Trotskyist activists such as Owen Gager and David Bedggood, and he contributed occasionally to journals such as "Dispute", "New Zealand Monthly Review" and "Spartacist Spasmodical".