The six-member board of Tata Sons held a marathon meeting on Friday, during which the heads of five heavily loss-making group companies presented their turnaround plans. With three board seats vacant, including one representing the Tata Trusts, the board currently has only six members. Those present at the meeting included Natarajan Chandrasekaran, Noel Tata, Venu Srinivasan, Harish Manwani, Anita M George and Saurabh Agrawal, sources said.