Jake is totally correct, DRLs must be fitted within strict guidlines (European Union Directive 2008/89/EC), once fitted your vehicle has to abide by those rules also when it comes to a Ministry of Transport test or inspection.
"European Union Directive 2008/89/EC requires all passenger cars and small delivery vans first type approved on or after 7 February 2011 in the EU to come equipped with daytime running lights. The mandate will extend to trucks and buses in August 2012. Functional piggybacking, such as operating the headlamps or front turn signals or fog lamps as DRLs, is not permitted; the EU Directive requires functionally specific daytime running lamps compliant with ECE Regulation 87 and mounted to the vehicle in accord with ECE Regulation 48. DRLs compliant with R87 emit white light of between 400 and 1200 candela[SUP]."[/SUP]