The Town and Country Planning (General Permitted Development) Order 2015 (the GPDO) at Schedule 2, Part 2, provides that the following is permitted development:
“Class A – gates, fences, walls etc.
A. Permitted development
The erection, construction, maintenance, improvement or alteration of a gate, fence, wall or other means of enclosure.”
Development not permitted is then set out at Class A.1:
“Development is not permitted by Class A if—
(c) the height of any gate, fence, wall or other means of enclosure maintained, improved or altered would, as a result of the development, exceed its former height or the height referred to in paragraph (a) or (b) as the height appropriate to it if erected or constructed, whichever is the greater; or
(d) it would involve development within the curtilage of, or to a gate, fence, wall or other means of enclosure surrounding, a listed building”.
The point to note here is that the ‘alteration’ of a wall which provides a means of enclosure is permitted development; since conservation areas are not excluded by virtue of Class A.1 then the alteration of such a wall in a conservation area is permitted development.
Section 55(2)(g) Town and Country Planning Act 1990 (TCPA90) states:
“(2) The following operations or uses of land shall not be taken for the purposes of this Act to involve development of the land—
(g) the demolition of any description of building specified in a direction given by the Secretary of State to local planning authorities generally or to a particular local planning authority.”
The current direction is The Town and Country Planning (Demolition - Description of Buildings) Direction 2021. It provides as follows at paragraph 3:
“Demolition not to be taken to involve development of land
3. (1) Subject to sub-paragraph (2), the demolition of the following descriptions of building shall not be taken, for the purposes of the Town and Country Planning Act 1990, to involve development of land:
(a) any building the cubic content of which, measured externally, does not exceed 50 cubic metres; (b) the whole or any part of any gate, fence, wall or other means of enclosure.
(2) The descriptions of building in sub-paragraph (1) do not include:
(a) the whole or any part of any gate, fence, wall or other means of enclosure in a conservation area; (b) a statue, monument or memorial.”
The full or partial demolition of a wall that provides a means of enclosure in a conservation area is therefore “development”.
The GPDO at Schedule 2, Part 11 provides that the following is permitted development:
“C. Permitted development
Any building operation consisting of the demolition of the whole or any part of any gate, fence, wall or other means of enclosure.”
Development not permitted is then set out at Class C.1
“Development not permitted
Development is not permitted by Class C if the demolition is “relevant demolition” for the purposes of section 196D of the Act (demolition of an unlisted etc. building in a conservation area).”
Section 196D Town and Country Planning Act 1990 (TCPA90) provides:
“(1) It is an offence for a person to carry out or cause of permit to be carried out relevant demolition without the required planning permission.”
“(3) In this section ‘relevant demolition’ means the demolition of a building that –
(a) is situated in a conservation area in England;
The definition of a ‘building’ in section 196D is to be found in section 336 TCPA90:
"“building” includes any structure or erection, and any part of a building, as so defined, but does not include plant or machinery comprised in a building;
The definition of ‘building’ in Art 2(1) of the GPDO, is also relevant:
“ “building” —
(a) includes any structure or erection and, except in [exceptions not relevant for present purposes] includes any part of a building; and
(b) does not include plant or machinery and, in Schedule 2, except in […] Class C of Part 11, does not include any gate, fence, wall or other means of enclosure”.
It is therefore clear that the full or partial demolition of any wall that provides a means of enclosure in a conservation area is ‘relevant demolition’ and an offence.
Since the alteration of a wall that forms a means of enclosure in a conservation area is permitted development, and since the full or partial demolition of that same wall would not be permitted development, but could constitute an offence it is necessary to consider what the statutory draftsman intended by ‘alteration’, and the distinction between that and ‘demolition’.
The leading case on what constitutes ‘relevant demolition’ pursuant to section 196D is Barton v SSHCLG  EWHC 573 (Admin); this related to the removal of a pedestrian gate, lintel and stonework forming part of a boundary wall in a conservation area. The total amount removed was 1m of gate and 2.5m of wall in a wall stretching 25m in length. The High Court confirmed that whether the works amounted to ‘alteration’ or ‘demolition’ was a matter of fact and degree, but specifically held that how much wall had been removed in the context of the overall wall was not relevant:
“the inspector made no error of law in focusing on what had been removed, rather than upon what had been removed in the context of the wall as a whole.”
The judge went on to state that the Inspector having come to a conclusion that the works were ‘demolition’ (the only works involved in this case were works of demolition, there being an absence of any other works), she was not obliged to go on to consider if the works might amount to an ‘alteration’ and therefore be permitted pursuant to Schedule 1, Part 2, Class A of the GPDO.