I found the original data reported here from a report in 2014, why the telegraph is writing about it in 2016 is ??
http://content.tfl.gov.uk/centre-line-removal-trial.pdf
On three short segments of highway up to 650 meters, they removed the center markings and speeds lowered especially when there were oncoming cars from average speeds that were at or above the 30 MPH posted limit to still above to below the postings. All these streets were resurfaced and a series of side stripes were included in all of them both marking the side of the road surface and bike/bus lanes. All the streets have street lights. The report indicates that speeds were recorded at non-peak times but does not report whether night conditions were monitored or just daytime. Here are a before and after set of markings from the report: