‘Since the consequences of failing to serve a valid and timely payment notice or pay less notice can be severe (see ISG Construction Ltd v Seevic College1), it perhaps should come as no surprise that in recent cases, there has been increasing attention on the validity of the application for payment because, without this, there can be no “notified sum” due to the contractor and, therefore, no requirement to serve a payment or pay less notice.’
Hardwicke Chambers, 3rd February 2016
Source: www.hardwicke.co.uk