Tree preservation zone

There is a problem

reference: TPO 0006 (1966)/A8
name: BALSHAM Parish
tree-preservation-order: TPO 0006 (1966)
tree-preservation-zone-type: area
geometry: MULTIPOLYGON (((0.309743 52.133185,0.309643 52.133191,0.309634 52.133116,0.309590 52.132982,0.309512 52.132853,0.309473 52.132734,0.309412 52.132630,0.309433 52.132586,0.309521 52.132492,0.309512 52.132450,0.309132 52.131955,0.308809 52.131493,0.308921 52.131453,0.308994 52.131438,0.310384 52.131299,0.311307 52.131229,0.311293 52.131527,0.311316 52.131704,0.311370 52.131965,0.311474 52.132223,0.311579 52.132420,0.311678 52.132771,0.311525 52.132774,0.311531 52.132671,0.311496 52.132499,0.311470 52.132418,0.311422 52.132349,0.311358 52.132223,0.311203 52.131847,0.311152 52.131634,0.311124 52.131340,0.309621 52.131459,0.308995 52.131523,0.308965 52.131535,0.309137 52.131807,0.309543 52.132329,0.309669 52.132471,0.309658 52.132519,0.309589 52.132674,0.309629 52.132776,0.309635 52.132842,0.309670 52.132936,0.309743 52.133185)))
point: POINT (0.310256 52.131895)
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