Torchwood star Gareth David-Lloyd will make a guest appearances in an episode of The Bill

GDL, who starred as the now-dead Ianto Jones in the Doctor Who spinoff, will appear as Jeremy Preston.
Source: Digital spy
http://www.digitalspy.co.uk/soaps/s20/thebill/news/a183049/sloane-tointon-david-lloyd-for-the-bill.html