One September afternoon in 2011, then Trinamool Congress MP Somen Mitra received a call on his cellphone. “Madam wants to see you immediately,” he was told. A livid Mamata Banerjee asked Mitra whether he had written any letter to then prime minister Manmohan Singh about a sudden spurt in chit fund companies in the state. When he admitted he had, she sternly told him it was none of his business, recalls Mitra. “She warned me not to meddle in affairs which should be dealt with only by the finance ministry.”

Three years later, when the Central Bureau of Investigation is investigating the chit funds Mitra mentioned in his letter, suspended Rajya Sabha member and once Mamata’s blue-eyed boy Kunal Ghosh declared while being interrogated, “If there is one person who has benefited most from the chit fund-run media companies, it is Mamata Banerjee.”

Earlier this year, some were actually entertaining the possibility of Mamata Banerjee becoming the prime minister of the country in the event of a hung Parliament. This was endorsed...