The Bermuda National Grid 2000 (BNG) is a kind of Transverse Mercator projection. It is not a Universal Transverse Mercator (UTM) projection, as it has an origin and other parameters that are different from those used in UTM.
Grid Parameters: Origin latitude 32.0 degrees (North) Origin longitude -64.75 degrees (East) Scale 1.0 Reference ellipsoid WGS84 False easting 550,000.0 meters False northing 100,000.0 meters
References
Online resources: Convert from BNG to lat/lon in Google earth Eye4Software's online converter.