http://www.bailii.org/ew/cases/EWHC/Ch/2016/366.html

CPR r31.5 provides that at the first, or any subsequent, case management conference, the court will decide which disclosure order to make (from a menu of different orders, including standard disclosure). CPR r31.5(7) provides for disclosure of "any documents which it is reasonable to suppose may contain information which enables that party to advance its own case or to damage that of any other party, or which leads to an enquiry which has either of those consequences". This "enhanced disclosure" differs from, and is wider than, standard disclosure because of the inclusion of documents "which it is reasonable to suppose may contain information" which may lead to a "train of enquiry" (ie the so-called Peruvian Guano test).

In this case, Henderson J refused to make such an order, saying that it would be premature to do so. If there are gaps in the defendant's disclosure exercise, the first step should be to "make appropriately focused requests to [the defendants'] solicitors, and only if satisfactory responses are not forthcoming would any question of enhanced disclosure arise. Considerations of cost and proportionality are always of paramount importance in the context of disclosure, and as matters now stand it is far from clear to me that it will really be necessary to go beyond the standard disclosure which I have ordered".

He also cited, with approval, the judgment of Gloster J in Berezovsky v Abramovich [2010], in which an order for enhanced disclosure was also refused. She had held that an order for enhanced disclosure should be focused on an identifiable category of document, linked to specific issues. That is because it is an onerous burden on a disclosing party to have to decide if the train of enquiry test has been met in relation to each document. She too found that it would be better to apply for enhanced disclosure (if necessary) only after standard disclosure has taken place.