The Newbury Town Library bid farewell last week to its longtime children’s librarian, Laurie Collins. As of this Tuesday, she will be children’s librarian at Ipswich Public Library. Collins joined the Newbury library 12 years ago, quickly establishing “great relationships’’ with children and “legendary’’ story hours, according to library trustee Lois Smith. “The children will miss her very much,” Smith said in a prepared statement, “but their mothers will miss her even more.’’ The library has taken budget hits in recent years. Officials did not respond to queries about whether Collins’s post would be filled.