"Unless you challenge it (which is not always a bad option), and then go to court and get ''charged'' with excess speed, which would be a different scenario, and i suppose would show up on a CRB check."
Incorrect. Been there done it. It is a civil offence, not a criminal. it will NOT be picked up b y anyone unless they see your paper counter-part. points are 'reset' after 3 years, and evidence (i.e. endorsment on paper) 'wiped' after 4 years.