Other height datums in use across Great Britain

As discussed in section 5.3, ODN is the national height datum used across mainland Great Britain. There are, however, a number of other British height datums that are used on the surrounding islands. The main ones being; Lerwick on the Shetland Islands, Stornoway on the Outer Hebrides, Douglas on the Isle of Man and St. Marys on the Scilly Isles. All of these height datums are incorporated within the National Geoid Model OSGM15.