https://www.lawtel.com/UK/FullText/AC9602003QBD(Comm).pdf

In 2013, a "menu" of disclosure order options was introduced into CPR 31.5. Anecdotal evidence suggests that the courts have been generally reluctant to depart from standard disclosure in most cases. However, in this case there was a dispute about some 2,500 transactions and the bank argued that disclosure relating to all of these transactions would be likely to take more than a year at a cost of more than £2 million. It therefore proposed that there should be a disclosure of 10 per cent of the transactions, to be selected on a random basis.

That sampling approach was accepted by Males J, on the basis that it was accepted that if that disclosure did not prove to be sufficient, the bank might be ordered to make full disclosure later on of all the transactions, even if that would put the 2018 trial date in jeopardy