No need to shout. please see
Site Rules:
http://www.theanswerbank.co.uk/Info/Rules/ about typing all in capitals.
"THE BOTTOM LINE IS HE BRAKED FOR NO APPARENT REASON"
He doesn't need a reason to brake, he can jump on the brakes for no other reason than he thinks you are too close behind him or because he thought he saw a flying elephant, it makes no difference, you should have been far enough away from him to allow you to stop safely.
"I DON'T REALLY CARE WHAT THE INSURANCE CO THINK"
Strange thing not to care about, end if the day it's them that decides who's to blame.
"NOR DID I REALLY THINK ABOUT THE LEGAL IMPLICATIONS OF OVER TAKING IN THE MIDDLE LANE"
Just because you didn't think of the legal implications doesn't suddenly make it legal.
"I JUST WANTED TO AVOID A CRASH."
I'd suggest if you want to avoid a crash in future then you leave a safe stopping distance between you and the car in front.
Anyhow, just leave it to your insurance company, I'm sure they will love to hear that you had to swerve to avoid a car because you couldn't stop in time.
You might not want to mention you couldn't stop in time to the police though, otherwise you may find your self on a charge of driving without due care and attention as well.