Before you buy land.

Both halves are documents somebody already holds. The notice, the approved drawing list and every condition-discharge decision sit on the council's public register. Beginning development means carrying out a material operation, which is a defined statutory list rather than a judgement, and it reaches as far down as digging a foundation trench. The catch is that the start only counts if it was lawful: where a condition goes to the heart of a permission, work done before it was discharged does not begin the development at all. A certificate of lawfulness can confirm operations carried out were lawful, and once one is in force that lawfulness is conclusively presumed. What expiry does to a consent, and what a lapsed one is still worth, is set out in the guide to development potential.

It works because there is no right to buy it. Where the only usable access crosses ground in somebody else's title, that owner is under no obligation to sell, and knows what the release is worth. There is no legal route round it either: the statute that lets a court order access over a neighbour's land is confined to preserving what already stands and does not reach new development. Valuers price the release as a share of the uplift it unlocks rather than as the value of the ground. The one-third figure that circulates is called a misconception by the government's own valuation guidance, which puts the starting point nearer a half; awards have run from fifteen per cent to fifty. Two checks find most of these before an offer: the title plan against the site plan, and the highway authority's record of what road length has actually been adopted.

The levy is a charge per square metre, and it is permissive: an authority only charges it where it has adopted a charging schedule, so the first question is whether one is in force. Where it is, liability is assumed by serving a notice before development commences, and afterwards it can only be passed on by a transfer notice. The chargeable amount is registered as a local land charge against the site, so it follows the land rather than the person who applied. Reliefs carry conditions of their own: the self-build and residential annexe exemptions are clawed back if the property is sold or let within three years of its completion certificate.

The local land charges search returns what is registered against the land: conditions on earlier permissions, tree preservation orders, listing, financial charges. A section 106 obligation is itself a local land charge, and so is a levy charge, so both surface there. The enquiries of the local authority add the decisions already made about the property, the adoption status of the roads and any recorded right of way. Every one of those questions is asked in the past tense. Neither search models a layout, tests an access, prices an abnormal or predicts a committee, and neither reaches the neighbour's land beyond contamination and a two hundred metre radius on road and rail schemes, so next door needs its own search. Why a site fails in principle, which is the other half of the question, is set out in the guide to why development sites fail.

Five things can be reserved for later approval: access, appearance, landscaping, layout and scale. Scale means the height, width and length of the buildings, not how many of them there are, so the quantum is not a reserved matter at all. It is fixed at outline, in the description or in a condition, and a submission that exceeds it falls outside the permission. What reserved matters settles is whether a layout can hold that number once highway geometry, drainage, separation distances and parking are applied at once. It can fall short as readily as confirm it. An outline also runs on two clocks rather than one: a period in which to apply for approval of the reserved matters, and a further period from the last of those approvals in which to begin. Miss either and the consent is gone.

The route is a diversion or stopping-up order, made because development authorised by a planning permission would otherwise block the path. It covers footpaths, bridleways and restricted byways; anything carrying vehicular rights goes down a different statutory route. Since 2013 the order can be made once the planning application is in, rather than waiting for the decision, but it cannot be confirmed until the permission has actually been granted. It carries its own notice period, its own objection route and the possibility of a public inquiry if objections are not withdrawn. Guidance is clear that a permission is not by itself a reason to make or confirm one. On a site crossed by a well-used path, that is a programme risk worth pricing at the offer.

That list is short because all of it exists already and none of it costs anything to produce. Add the pre-application correspondence if there is any, the reports the application was supported by, and any survey the seller has commissioned, noting that a survey addressed to somebody else may not be relied on without the author's agreement. What a seller cannot supply is as informative as what they can. A consent with no discharge decisions behind it has not been started; a site plan that does not match the title plan means one of the two is wrong; and a marketing report describing the site's potential was written for the seller and is not an appraisal.