VERTCRS["St. Marys height",
    VDATUM["St. Marys"],
    CS[vertical,1],
        AXIS["gravity-related height (H)",up,
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["Geodesy, engineering survey."],
        AREA["United Kingdom (UK) - Great Britain - England - Isles of Scilly onshore."],
        BBOX[49.86,-6.41,49.99,-6.23]],
    ID["EPSG",5749]]