Tree preservation zone

There is a problem

reference: TPO 0006 (1966)/A20
name: BALSHAM Parish
tree-preservation-order: TPO 0006 (1966)
tree-preservation-zone-type: area
geometry: MULTIPOLYGON (((0.320999 52.133765,0.320881 52.133832,0.320836 52.133833,0.320780 52.133810,0.320558 52.133585,0.320444 52.133417,0.320371 52.133348,0.320332 52.133295,0.320287 52.133258,0.320188 52.133137,0.320039 52.132915,0.319999 52.132869,0.319874 52.132770,0.319801 52.132760,0.319642 52.132787,0.319311 52.132871,0.319265 52.132870,0.319225 52.132771,0.319241 52.132737,0.319447 52.132658,0.319882 52.132553,0.320491 52.132388,0.320567 52.132401,0.320632 52.132427,0.320678 52.132484,0.320631 52.132535,0.320565 52.132587,0.320513 52.132653,0.320484 52.132763,0.320527 52.132856,0.320620 52.132928,0.320963 52.133145,0.321039 52.133349,0.321081 52.133519,0.321080 52.133569,0.320999 52.133765)))
point: POINT (0.320396 52.133034)
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