Modern crash protection

Some time ago, a fellow reader mentioned about the crash protection of our trains.

Can someone please put my mind at rest, as I’m struggling to see how much protection passengers have on a Thameslink Class 700 unit, compared with those of the Bombardier Class 378/9s or the newer Class 720s.

I use all these units to and from work (Royston-Cambridge) so it would be very interesting to see how these units compare?

Robert Black, Cambridgeshire