That is irrelevant though especially since there is a question mark about what the remaining paddock is being classed as. I grow vegetables in my garden, but that doesn't make it an agricultural field. Lemony says fruit trees have been planted, which are found in both agricultural orchards and gardens. A judgement call has to be made about what the land is, scale will come into play, but it is hard to write down hard and fast rules.
If the ultimate goal is to put horses on there then that will need planning permission anyway (if you will be bringing hay to feed them).
Nope. 'Agricultural' is a planning class, which allows use for agriculture.
'Residential' is a planning class (which extends to the curtilage of a house) which permits living, the growing of crops for own use and for sale, and the keeping of livestock the same. That is, it includes agriculture.
The freedom to feed yourself and live off your land is an ancient right that has never been taken away. You own it: you can dig it, and your hens can scratch it: and you can sell the eggs. No planning class takes away that right.
So: A residential property has standing permission to live, sleep, take your leisure, grow veg, keep livestock, sell the produce
A field lacking residential use has standing permission to grow, picnic, store chattels, keep livestock, sell the produce.
A field (agricultural use only) at the back of your house is not part of your residence, your garden, and mustn't be treated as such. No summer houses or sheds, (unless for the needs of an agricultural business), no swings and slides etc. But you can grow what you like and keep livestock on it to your heart's content. If there is a justified agricultural need you can make hard paths and hardstandings, lay in water; you can fit a toilet and drains, lay on electricity and a phone.
Here's the rules.
" Class B – agricultural development on units of less than 5 hectares
Permitted development
B.
The carrying out on agricultural land comprised in an agricultural unit, of not less than 0.4 but less than 5 hectares in area, of development consisting of—
(a)
the extension or alteration of an agricultural building;
(b)
the installation of additional or replacement plant or machinery;
(c)
the provision, rearrangement or replacement of a sewer, main, pipe, cable or other apparatus;
(d)
the provision, rearrangement or replacement of a private way;
(e)
the provision of a hard surface;
(f)
the deposit of waste; or
(g)
the carrying out of any of the following operations in connection with fish farming, namely, repairing ponds and raceways; the installation of grading machinery, aeration equipment or flow meters and any associated channel; the dredging of ponds; and the replacement of tanks and nets,
where the development is reasonably necessary for the purposes of agriculture within the unit.
Development not permitted
B.1 Development is not permitted by Class B if—
(a)the development would be carried out on a separate parcel of land forming part of the unit which is less than 0.4 hectares in area;
(b)the external appearance of the premises would be materially affected;
(c)any part of the development would be within 25 metres of a metalled part of a trunk road or classified road;
(d)it would consist of, or involve, the carrying out of any works to a building or structure used or to be used for the accommodation of livestock or the storage of slurry or sewage sludge where the building or structure is within 400 metres of the curtilage of a protected building;
(e)it would relate to fish farming and would involve the placing or assembly of a tank on land or in any waters or the construction of a pond in which fish may be kept or an increase (otherwise than by the removal of silt) in the size of any tank or pond in which fish may be kept; or
(f)any building for storing fuel for or waste from a biomass boiler or an anaerobic digestion system would be used for storing waste not produced by that boiler or system or for storing fuel not produced on land within the unit.
B.2 Development is not permitted by Class B(a) if—
(a)the height of any building would be increased;
(b)the cubic content of the original building would be increased by more than 10%;
(c)any part of any new building would be more than 30 metres from the original building;
(d)it would consist of the extension or provision of any agricultural building on an established agricultural unit (as defined in paragraph X of Part 3 (changes of use) of this Schedule) where development under Class Q or S of Part 3 (changes of use) of this Schedule has been carried out within a period of 10 years ending with the date on which development under Class B(a) begins;
(e)the development would involve the extension, alteration or provision of a dwelling;
(f)any part of the development would be carried out within 5 metres of any boundary of the unit; or
(g)the ground area of any building extended by virtue of Class B(a) would exceed 465 square metres.
B.3 Development is not permitted by Class B(b) if—
(a)the height of any additional plant or machinery within 3 kilometres of the perimeter of an aerodrome would exceed 3 metres;
(b)the height of any additional plant or machinery not within 3 kilometres of the perimeter of an aerodrome would exceed 12 metres;
(c)the height of any replacement plant or machinery would exceed that of the plant or machinery being replaced; or
(d)the area to be covered by the development would exceed 465 square metres calculated as described in paragraph D.1(2)(a) of this Part.
B.4 Development is not permitted by Class B(e) if the area to be covered by the development would exceed 465 square metres calculated as described in paragraph D.1(2)(a) of this Part.
Conditions
B.5—(1) Development permitted by Class B and carried out within 400 metres of the curtilage of a protected building is subject to the condition that any building which is extended or altered, or any works resulting from the development, is not used for the accommodation of livestock except in the circumstances described in paragraph D.1(3) of this Part or for the storage of slurry or sewage sludge, for housing a biomass boiler or an anaerobic digestion system, for storage of fuel or waste from that boiler or system, or for housing a hydro-turbine.
(2) Development consisting of the extension or alteration of a building situated on article 2(4) land or the provision, rearrangement or replacement of a private way on such land is permitted subject to—
(a)the condition that the developer must, before beginning the development, apply to the local planning authority for a determination as to whether the prior approval of the authority will be required as to the siting, design and external appearance of the building as extended or altered or the siting and means of construction of the private way; and
(b)the conditions set out in paragraphs A.2(2)(ii) to (vi) of this Part.
(3) Development is permitted by Class B(f) subject to the following conditions—
(a)that waste materials are not brought on to the land from elsewhere for deposit unless they are for use in works described in Class B(a), (d) or (e) and are incorporated forthwith into the building or works in question; and
(b)that the height of the surface of the land will not be materially increased by the deposit.
(4) Development is permitted by Class B(a) subject to the following conditions—
(a)where development consists of works for the significant extension or significant alteration of a building and—
(i)the use of the building or extension for the purposes of agriculture within the unit permanently ceases within 10 years from the date on which the development was substantially completed; and
(ii)planning permission has not been granted on an application, or has not been deemed to be granted under Part 3 of the Act, for development for purposes other than agriculture, within 3 years from the date on which the use of the building or extension for the purposes of agriculture within the unit permanently ceased,
then, unless the local planning authority have otherwise agreed in writing, the extension, in the case of development consisting of an extension, must be removed from the land and the land must, so far as is practicable, be restored to its condition before the development took place, or to such condition as may have been agreed in writing between the local planning authority and the developer;
(b)where an appeal has been made, under the Act, in relation to an application for development described in paragraph (a)(ii), within the period described in that paragraph, that period is extended until the appeal is finally determined or withdrawn.
(5) Where development is permitted by Class B(a), within 7 days of the date on which the development is substantially completed, the developer must notify the local planning authority in writing of that fact."
The Town and Country Planning (General Permitted Development) (England) Order 2015
PART 6
Agricultural and forestry
https://www.legislation.gov.uk/uksi/2015/596/schedule/2/part/6/made