We combine GALEX ( ultra-violet ; UV ) and SDSS ( optical ) photometry to study the recent star formation histories of \sim 100 field galaxies on the optical red sequence , a large fraction of which exhibit widespread signs of disturbed morphologies in deep optical imaging that are consistent with recent merging events . More than 70 % of bulge-dominated galaxies in this sample show tidal features at a surface brightness limit of \mu \sim 28 mag arcsec ^ { -2 } . We find that , while they inhabit the optical red sequence , they show a wide spread in their UV colours ( \sim 4 mags ) , akin to what has been discovered recently in the general early-type population . A strong correlation is found between UV colour and the strength of the tidal distortions , such that the bluest galaxies are more distorted . This strongly suggests that the blue UV colours seen in many nearby early-types are driven by ( low-level ) merger-induced star formation within the last 3 Gyrs , contributing less than 10 % of the stellar mass . If the ongoing mergers in this sample , which have a median mass ratio of 1:4 , are representative of the nearby red merger population , then less than \sim 25 % of the new stellar mass in the remnants is typically added through merger-induced star formation . While the dust extinction in the inter-stellar medium ( ISM ) in these galaxies is small ( E ^ { ISM } _ { B - V } < 0.1 ) , the local dust content of the star-forming regions is , on average , a factor of \sim 3 higher . Finally , we use our theoretical machinery to provide a recipe for calculating the age of the most recent star formation event ( t _ { 2 } ) in nearby ( z \lesssim 0.1 ) red early-type galaxies : \log t _ { 2 } { \color { black } \hskip { 3.6135 pt } \textnormal { [ Gyrs ] } } \sim 0.6 ^ { \pm 0.03 % } \times [ ( NUV - u ) - ( g - z ) -1.73 ^ { \pm 0.03 } ] , where NUV,u,g and z are the observed photometric magnitudes of the galaxies in the GALEX/SDSS filtersets .