Check ref: RM 2013 data suggests this should be OX27 339D (see check_date:ref for date of most recent check that confirmed the apparently erroneous OX27 559D)
last_checked
2020-08-27
note
Although this postbox is marked on OSM as OX27 339, when I used this postbox on Thursday 27.08.2020 the postbox number stated "OX27 559D".