Earlier this summer, the Supreme Court ruled in favour of a landowner who sold two 18th century urns without realising they were, in their own right, classed as listed buildings (and so subject to the protections of the listed buildings regime).

The urns in question were originally commissioned for Wrest Park in Bedfordshire. They were moved a number of times, ending up in the ownership of Major Dill, and located in Idlicote House. In 1966 Idlicote House was designated as a Grade II listed building, and in 1986 the urns were themselves designated as listed buildings. There is no record that the owner was ever notified.

Major Dill's son inherited Idlicote House and the urns in 1993. He was unaware that the urns were listed and sold them at auction in 2009.

The local planning authority found out about this, and notified Mr Dill that listed building consent had been required. Mr Dill then applied for consent, which was refused. An enforcement notice followed, requiring Mr Dill to reinstate the urns at Idlicot House. This would have been difficult, considering the urns were thought to have already left the country.

Mr Dill appealed the decision on several grounds, including that the urns were not "buildings".  Mr Dill's appeal was refused; the planning inspector took the view that the status of the urns in the list as "buildings" was determinative in itself. The status of the urns could not be challenged; he could not 'go behind' the listing and re-evaluate it. This view was upheld by the High Court and Court of Appeal.

The case ended up in the Supreme Court, where there were two issues to be decided; (1) whether an inspector could decide whether something on the list is a "building", and (2) what criteria are relevant in determining whether an item in its own right is a "building".

The Supreme Court decided in Mr Dill's favour:

1. Can an inspector determine whether something is a "building"?

The Court held that if the item is not a building, its mere inclusion in 'the list' does not make it one. Consequently, planning inspectors may now determine whether an item is indeed a building (or not), and so is validly included on the list (or not).

2. What criteria are relevant in determining if an asset is a "building"?

The Court did not come to a decision itself as to whether the urns were 'buildings'; this is a decision that the planning inspector is best placed to make, rather than the Court. However, the Court did hold that the relevant criteria are set out in a test called the Skerritts test; a threefold test which considers (1) size (2) permanence and (3) degree of physical attachment.

It seems likely that the extent to which items are inherently, intrinsically part of the history and design of the building will be an important consideration in relation to the 'permanence' limb in the Skerritts test.

What implications does this judgement have for owners of listed assets, and how can they avoid a similar legal battle?

This case emphasises how important it is for owners to check whether an item is listed before they move it, especially since removing a listed item without listed building consent is a criminal offence. The 'list' is now available on the Historic England website, so it is easier than ever for these enquiries to be made. Auction houses and galleries also have a role to play in due diligence before a sale.

Where an owner finds that their item is indeed listed, legal advice should be sought and discussions can be commenced with the local authority and Historic England regarding a potential de-listing.

It is important to note that Dill will only have consequences for those items which are listed and do not satisfy the Skerritts test. For example, many urns which are listed will indeed satisfy all limbs and are correctly listed.

While Dill has opened up a potential defence where an owner is faced with enforcement action, it is obviously important for the issue to be identified before matters progress to that stage.

Rosie Adcock is an associate at Boodle Hatfield