He was one of the People's Action Party's (PAP) MPs in one of its strongholds for 26 years. Now Dr Tan Cheng Bock is back - but as a challenger to his former party, and with ex-PAP cadres in tow, not to mention his knowledge of how the ruling party fights its election battles.

As to where he will stand, the secretary-general of Singapore's newest opposition party, the Progress Singapore Party (PSP), has everyone guessing whether he will return to his old stomping ground Ayer Rajah in the next general election.