Horrific crash and could have happened to anyone. Waiting at traffic lights then dead (at least it would have been instant).
From the various news reports and expert analysis it looks like it could be due to pilot error. The plane was apparently maintained to a very high standard (according to someone who flew it recently). The pilot, Andy Hill, was highly thought of though so surprising if he made an error, although the Red Arrows did not want to do their full display (because of conditions) so perhaps the conditions led to an error?