In 1967, he was elected to the 4th Lok Sabha from Contai constituency in West Bengal as a Praja Socialist Party (PSP) candidate.
He also made several efforts to make Government of India publish all secret files on Bose's death.
Even though the secret files were not published, Guha was one of the main vocal supporter of creating G D Khosla commission to re-investigate Bose's death in 1970.
Primarily due to Guhas's effort, then Indian Prime Minister Morarji Desai announced that Khosla Commission's statement was not the final words on Bose's death.
Soon after though, Guha's credibility took a serious blow when he produced a picture of Bose claiming it was a recent one that turned out to be fake.