A new and possibly dangerous chapter in Thailand's volatile political history begins on Sunday, when the country goes to the polls in an election widely expected to bring Yingluck Shinawatra, sister of exiled former leader Thaksin Shinawatra, to power.

For more than a decade following a bloody standoff with the army in 1992, Thailand had seemed to be settling down to stability and democracy, albeit one that still reserved considerable power for the monarchy and the military establishment. But in 2006 Thaksin, having been re-elected in a landslide the previous year, was confronted by popular demonstrations by the People's Alliance for Democracy, or "yellow shirts", and eventually overthrown in a military coup.