SE14 New Cross: why this London postcode has the number 14

After Lewisham, before Peckham

New Cross is SE14 because of the alphabet. SE1 is the South Eastern district office, and in the Post Office's list of March 1917 the offices after it follow by name: New Cross comes after Lewisham (SE13) and before Peckham (SE15).

See SE14 on the map