Did someone say there were no witnesses? In which case how do you prove "beyond reasonable doubt" that the cyclist was hit from behind rather than was filtering? Istm that if hit from behind, mirrors would be irrelevant.
There were witnesses, but not eye-witnesses. There was also no CCTV.
At the inquest officers from the Met Collision Investigation Unit thought it
more likely she was in front of the lorry. I'd infer from this that they could not be certain of the critical combination of circumstances that led to Eilidh's death, but given the available evidence this was their (qualified) conclusion.
A Class VI mirror does allow a driver to see directly in front of his cab. However, I do not know if the tipper truck involved was fitted with this mirror.