There are many, many reasons why speed limits exist, and while we may not always agree with the regulated speed, we all know, as drivers, that we should obey the law and drive within the prescribed limit. If you choose not to, the consequences are well known - points on your licence and a fine. This can also mean a driving ban if you rack up enough points. The minimum penalty is a £100 fine and 3 penalty points added to your licence - or the option to take a speed awareness course, but the fines are about to go up... and it could get very expensive!
Currently, if you're caught & convicted of doing over 50mph in a 30 limit or over 40mph in a 20, magistrates will consider 100% of your weekly earnings as a starting point for a fine. As of April 2017, you will earn a fine of between 125% - 175% of relevant weekly income. That's on top of 6 points and/or a 7 – 56 days disqualification.
Simple message - OBEY THE SPEED LIMITS!!