Increasingly light library board duty doubled pension of former senator

John A. Brennan Jr. won plaudits when he resigned after 19 years of service as a member of the Malden Public Library Board of Trustees, a volunteer seat he held despite his busy career as one of Beacon Hill’s most influential lobbyists.

But a closer look at the record shows that Brennan, a 63-year-old former state senator who departed the Legislature in 1990, barely attended monthly library board meetings during the last four years, missing 30 out of 36 meetings.