New London — More than five months after he was placed on paid administrative leave, longtime New London school administrator William “Tommy” Thompson was cleared to return to work this week, the union representing him has confirmed. Thompson, the former principal at New London High School, was the subject of an investigation by the school district for “possible unprofessional conduct and violation of Board Policies.” The school district has declined to discuss the reason for the investigation, whether it was completed or the circumstances of Thompson’s return. The district in the past has cited the case as a personnel matter.