Feeling inspired to visit Exbury Gardens? When I visited them recently I took my Garmin GPS receiver, and noted down some relevant waypoints. The route is very simple, and less than a hundred miles from London. From Central London, work your way out through Hammersmith, over Chiswick Bridge, past Richmond and Twickenham on the A316, and this will become the M3 at Sunbury, just past the Kempton Park reservoirs and Race Course. Otherwise you can pick up the M3 from junction 12 on the M25 London orbital motorway. Head on down towards Southampton, but take the M27 west towards Bournemouth at the end of the M3. About five miles on, turn off at junction 2 onto the A326 towards Hythe and Fawley. Then take the B3054 towards Beaulieu (pronounced "Byoo-lee"!) After two miles, turn left, then immediately right, at the junction. This is the final approach, and the gardens are well signposted three miles down this country lane.
The following table shows the grid reference co-ordinates, and Latitude and Longitude, of the major waypoints, including some motorway service stations. Should anyone making the journey be able to measure accurate distances, I would be pleased to add them to this page.
| Waypoint | OS Grid Reference | Latitude | Longitude |
|---|---|---|---|
| M25 junction 12 * | TQ 01785 67831 | 51° 24.020' N | 0° 32.292' W |
| Fleet services | SU 80354 55952 | 51° 17.819' N | 0° 50.933' W |
| Winchester services | SU 52422 36030 | 51° 07.266' N | 1° 15.142' W |
| Turn off at end of M3 | SU 44033 19579 | 50° 58.433' N | 1° 22.454' W |
| Join M27 | SU 40375 17991 | 50° 57.592' N | 1° 25.590' W |
| M27 services (Road Chef) | SU 39298 17864 | 50° 57.528' N | 1° 26.511' W |
| A326 (M27 junction 2) | SU 33701 16417 | 50° 56.769' N | 1° 31.300' W |
| B3054 | SU 40988 05913 | 50° 51.073' N | 1° 25.147' W |
| Exbury Road | SU 40115 03267 | 50° 49.650' N | 1° 25.909' W |
| Exbury Gardens | SU 42403 00575 | 50° 48.187' N | 1° 23.979' W |
* The location given for the M25 junction 12 (M3 turn off) is approximate - it obviously depends which way you approach it - watch out for the signs!
The British OS (Ordnance Survey) Grid is based on major squares with 100 kilometre sides. The 5-digit reference thus gives a resolution down to 1 metre!
The mean diameter of the Earth is 7926.2 miles (12756 Km - from the Times Comprehensive Atlas of the World, Millennium Edition), so the circumference is 24,901 miles. One degree of Latitude will thus be 69.169 miles; a minute of arc will be 1.153 miles (2029 yards), and so the third decimal place will represent just over two yards.
The Longitude resolution is higher (less distance) as the circle becomes smaller the further away from the equator you go. From a 7926.2 mile diameter at the equator, it reduces to 5009.3 miles at Exbury's latitude, thus giving a resolution of 1.282 yards for the final digit.
Note the careful use of the term resolution - the accuracy is much worse than that. GPS accuracy used to be quoted as about 100 yards, but that was in the days when "Selective Access" was active. This was a fiendish ploy by the US military who operate the GPS satellites to keep the highest accuracy for themselves, whilst deliberately introducing a small random error for commercial uses. However, that nice President Clinton ordered this be deactivated from the 2nd of May, 2000, from when an accuracy about ten times greater has been readily achievable.
The figures above were obtained as accurately as possible whilst driving, and should be within 20-30 yards at most.