This British Railways Sector was formed on this day in 1986 under the leadership of Chris Green. It comprised the following area, replacing in its area the BR Regions that had existed since Nationalisation in 1948
It absorbed the entire London suburban network as well as Kent, Surrey, Sussex, Hampshire and beyond to Weymouth, Salisbury and Exeter, plus the Isle of Wight; north to Bedford, Northampton and Banbury; west to Bedwyn; east to Kings Lynn, Harwich, Clacton and Shoeburyness In terms of BR regions, it encompassed the entire Southern (re-branded as Southeast, Central and Southwest), plus parts of the Western, Midland and Eastern (re-branded West, North and East – West subsequently became Thames & Chiltern and East became Anglia).
There was a “tube style” system map across the network; red platform lamp posts and a NSE logo and livery on rolling stock and station signage. Electronic clocks on all platforms and more staff.
It lasted until 1994 when the whole system was prepared for privatisation by the creation of line management the precursor to the letting of private franchises
For much more info see the Network South East Society site http://www.nsers.org/what-was-nse.html