3The enlargement, improvement or other alteration, as often as may be required, of any such building as is mentioned in paragraph l(a) or (b), or any building substituted for such a building by the carrying out of any such operations as are mentioned in that paragraph, so long as the cubic content of the original building is not substantially increased or exceeded.
4(1)The carrying out, on land which was used for the purposes of agriculture or forestry at a material date, of any building or other operations required for the purposes of that use.
(2)Sub-paragraph (1) does not apply to operations for the erection, enlargement, improvement or alteration of dwellinghouses or of buildings used—
(a)for the purposes of market gardens, nursery grounds or timber yards, or
(b)for other purposes not connected with general farming operations or with the cultivation or felling of trees.
5The winning and working, on land held or occupied with land used for the purposes of agriculture, of any minerals reasonably required for the purposes of that use, including—
(a)the fertilisation of the land so used, and
(b)the maintenance, improvement or alteration of buildings or works on the land which are occupied or used for those purposes.
6In the case of a building or other land which—
(a)at a material date was used for a purpose falling within any general class specified in the [S.I. 1948/955.] Town and Country Planning (Use Classes for Third Schedule Purposes) Order 1948, or
(b)having been unoccupied on and at all times since 1st July 1948, was last used (otherwise than before 7th January 1937) for any such purpose,
the use of that building or land for any other purpose falling within the same general class.
7In the case of any building or other land which at a material date was in the occupation of a person by whom part only of it was used for a particular purpose, the use for that purpose of any additional part of the building or land not exceeding—
(a)one-tenth of the cubic content of the part of the building used for that purpose on 1st July 1948 or, if later, the date when the building began to be so used, or
(b)one-tenth of the area of the land so used on that date,
as the case may be.
8The deposit of waste materials or refuse in connection with the working of minerals, on any land comprised in a site which at a material date was being used for that purpose, so far as may be reasonably required in connection with the working of those minerals.