kOLKATA, Feb. 24 -- Former railway minister Mukul Roy, once regarded as West Bengal Chief Minister Mamata Banerjee's most trusted lieutenant and the TMC's principal strategist, died of cardiac arrest at a private hospital here early on Monday. He was 71, and is survived by his son, Subhranshu Roy. He breathed his last around 1.30 am at the hospital in Salt Lake, Subhranshu Roy said. He had been suffering from multiple ailments and was in and out of the hospital over the past two years. Family members said he had also been diagnosed with dementia and had recently gone into a coma. His body will be taken to his residence before the last rites are performed later in the day, they said. A former Union minister and two-time Rajya Sabha member from West Bengal, Roy's four-decade-long political journey saw his stints in the Congress, TMC and the BJP. His political career began with the Youth Congress, before he joined hands with Banerjee when she broke away from the grand old party to form the Trinamool Congress in 1998. As a founding member, he quickly emerged as one of the key organisational pillars of the fledgling party and went on to serve as its general secretary. FULL REPORT ON P4...