2006–07 National Division Three South

The 2006–07 National Division Three South was the seventh season (20th overall) of the fourth division (south) of the English domestic rugby union competition using the name National Division Three South. New teams to the division only included promoted teams from lower leagues (there had been no relegation from the 2005–06 National Division Two) including Canterbury who came up as champions of London Division 1, while Chinnor (champions) and Clifton (playoffs) came up from South West Division 1. The league system was 4 points for a win, 2 points for a draw and additional bonus points being awarded for scoring 4 or more tries and/or losing within 7 points of the victorious team. In terms of promotion the league champions would go straight up into National Division Two while the runners up would have a one-game playoff against the runners up from National Division Three North (at the home ground of the club with the superior league record) for the final promotion place.

In what was a close title race, Southend edged out Westcombe Park to take the title by just two points (and promotion to the 2007–08 National Division Two), despite the London side having a much superior for and against points record. Westcombe Park would join Southend in the following seasons National Division Two by defeating 2006–07 National Division Three North runners up Tynedale at Goddington Dene in the promotion playoff. At the other end of the table newly promoted Chinnor went straight back down as the first team to be relegated, followed closely by Cheltenham-based side Old Patesians. Hertford were the final team to go down, being much more competitive but eventually finishing two points below 11th placed Clifton. Chinnor and Old Patesians would join South West Division 1 while Hertford would fall to London Division 1.