An off-duty police officer who was killed after being struck by a lorry while helping at the scene of another crash in North Yorkshire was “the very best of us”, local leaders have said. PC Rosie Prior and a motorist, Ryan Welford, were standing on the verge of the A19 when they and a third person were struck by a heavy goods vehicle shortly before 9am on Saturday, police said. Prior and Welford, 41, from Knaresborough, who had been involved in the first collision, both died at the scene. A teenage boy who was a passenger in Welford’s car was