Eastern Counties 1 (1987–1993) The original Eastern Counties 1 was a tier 8 league with promotion up to
London 3 North East and relegation down to
Eastern Counties 2.
Eastern Counties 1 (1993–1996) The creation of
National 5 South meant that Eastern Counties 1 dropped from a tier 8 league to a tier 9 league for the years that National 5 South was active. Promotion and relegation continued to
London 3 North East and
Eastern Counties 2 respectively.
Eastern Counties 1 (1996–2000) The cancellation of
National 5 South at the end of the 1995–96 season meant that Eastern Counties 1 reverted to being a tier 8 league. Promotion and relegation continued to
London 3 North East and
Eastern Counties 2 respectively.
Eastern Counties 1 (2000–2009) The introduction of
London 4 North East ahead of the 2000–01 season meant Eastern Counties 1 dropped to become a tier 9 league with promotion to this new division. Relegation continued to
Eastern Counties 2 - split into north and south regional divisions between 2000 and 2003.
Eastern Counties 1 (2009–2017) Eastern Counties 1 remained a tier 9 league despite national restructuring by the
RFU. Promotion was to
London 3 North East (formerly London 4 North East) and relegation to
Eastern Counties 2, which split into three regional divisions - north, south, west - from the 2014–15 season onward.
Eastern Counties 1 (2017–present) The cancellation of
London 3 North East and subsequent introduction of
London 3 Eastern Counties ahead of the 2017–18 meant that Eastern Counties 1 remained a tier 9 league with promotion to this new division. Relegation continued to the regionalised
Eastern Counties 2 (north, south, west). ==Promotion play-offs==