“…The region encompassing Great Britain and the western North Sea has excellent gravity coverage both on-and offshore (approximately one observation per square kilometer) and, as such, the area has been subject to a number of gravimetric geoid computations (e.g., Olliver, 1980;Stewart & Hipkin, 1990;Featherstone & Olliver, 1994;Hipkin, 1995). Since 1990, short-wavelength (<100-km) GPS/orthometric height geoid control has been available for the United Kingdom, with accuracy quoted by Hipkin (1995) of the order of 1-2 cm.…”