The line of accurately surveyed points running north from Dunnose to Clifton in Yorkshire provide the basis for triangulation to determine the positions of all other locations in Britain.

[1] The bay between Dunnose and St. Catherine's Point to the southeast has a rocky bottom and can be hazardous, since the charts may not show all the submerged rocks.

[2] Around 1800 Dunnose was taken as a base point for a triangulation of Great Britain, in which Captain William Mudge measured a section of the meridional arc running up into Yorkshire.

[6] Doubts were cast on the accuracy of the measurements in 1812, when Joseph Rodriguez pointed out that, if they were accurate, the length of a degree of longitude did not vary with latitude as it should if the earth were flattened at the poles.

Dunnose also was the origin (meridian) of the 6 inch and 1:2500 Ordnance Survey maps for the central group of English counties: they were Derbyshire, Nottinghamshire, Lincolnshire, Staffordshire, Warwickshire, Worcestershire, Leicestershire, Rutlandshire, Northamptonshire, Gloucestershire, Oxfordshire, Buckinghamshire, Wiltshire, Berkshire, Hampshire and the Isle of Wight.