This study is based on the WSRT observations of the Lockman Hole field at 1.4GHz (Prandoni et al., 2018MNRAS.481.4548P). The data consist of 16 individual pointings, each observed for a full synthesis of 12-hrs between December 2006 and January 2007. The centre of the mosaic was chosen to be at RA=10:53:16.6; DE=+58:01:15 (J2000). <P />We present a new deep-field analysis of polarised sources in the Lockman Hole at 1.4GHz, using a bespoke polarised mosaic with a central RMS of 7uJy/beam. We find 150 polarised sources in an area of 6.5deg<SUP>2</SUP> out of 1708 total-intensity sources in this field (8.8%). This equates to a polarised source density of 23deg<SUP>-2</SUP>. <P />(3 data files).