Tree preservation zone

There is a problem

reference: TPO 0006 (1966)/A24
name: BALSHAM Parish
tree-preservation-order: TPO 0006 (1966)
tree-preservation-zone-type: area
geometry: MULTIPOLYGON (((0.327120 52.134186,0.325980 52.134070,0.325968 52.134047,0.325824 52.133592,0.325822 52.133559,0.325871 52.133280,0.326758 52.133299,0.327011 52.133229,0.326934 52.133156,0.326893 52.133103,0.326826 52.133109,0.326799 52.133048,0.326807 52.132998,0.326945 52.132954,0.326986 52.132935,0.327005 52.132917,0.327019 52.132884,0.327017 52.132861,0.326944 52.132796,0.326955 52.132777,0.326972 52.132769,0.326947 52.132704,0.327239 52.132659,0.327176 52.132453,0.326410 52.132462,0.326221 52.132221,0.326234 52.132197,0.326283 52.132157,0.326344 52.132139,0.326425 52.132129,0.326638 52.132129,0.326715 52.132103,0.326886 52.132102,0.327100 52.132114,0.327237 52.132166,0.327686 52.132214,0.327664 52.132264,0.327685 52.132475,0.327724 52.132664,0.327833 52.132927,0.327936 52.133133,0.328036 52.133299,0.328072 52.133330,0.328153 52.133439,0.327370 52.133700,0.326967 52.133817,0.327066 52.134027,0.327120 52.134186)))
point: POINT (0.326968 52.133205)
notes
entry-date: 2021-09-01
start-date: start-date must be a real date
1966-12-12
end-date

Your dataset is missing the start-date column.

The Tree preservation zone guidance explains how to fix the issue:

The date that the tree preservation order came into force, written in YYYY-MM-DD format.

Example: 1984-03-28