In the news

Looks like this is the guidance here
http://www.cps.gov.uk/legal/p_to_r/road_traffic_offences_guidance_on_prosecuting_cases_of_bad_driving/#a20
Guess this is the most relevant part

Driving carelessly or driving dangerously do not, on their own, amount to unlawful acts for the purpose of unlawful act manslaughter. Andrews v DPP [1937] A.C. 576

Unlawful act manslaughter should, therefore, only be charged instead of causing death by dangerous driving where there is evidence that the driver either intended to cause injury to the victim or was reckless as to whether injury would be caused.

Not sure how that ties in with the current case though.