Planning permission is not required for the erection of walling, fencing or gates not exceeding 1m in height in the area in front of any elevation fronting onto a highway.
To the rear of a dwelling (not fronting a highway) walling, fencing and gates may be up to 2m. Fencing must be constructed of vertical posts with space between them and not of a solid construction.
For a full copy of the Order click this link. Class 16, page 17 refers.