Who is middlesex mutual assurance? Available Contacts – Free Plug-In! Middlesex Mutual Assurance underwrites and provides business and inpidual property/casualty insurance to its customers in the eastern US. Along with its sister company Holyoke Mutual, it operates under the MiddleOak brand of auto, homeowners, umbrella, flood, watercraft, and specialty insurance.Where is the middlesex insurance company in stevens point? Middlesex Insurance Company. 1800 North Point Drive. Stevens Point, WI 54481-1253. (715) 346-6000. The Middlesex Insurance Company is a wholly owned subsidiary of the Sentry Insurance Group.Who is the parent company of middlesex? The Sentry Insurance Group, Middlesex’s parent company, takes pride in being one of the biggest and strongest mutual insurance corporations in the country. They boast of over $10 billion in assets as well as $3 billion in policyholder surplus.What kind of insurance is middleoak insurance company? MiddleOak Insurance Company offers property and casualty insurance for multi-family buildings. MiddleOak Insurance ratings are an A+ (Superior) with A.M. Best. MiddleOak Insurance Company car insurance is not available at this time.