>>>It was amber and the police wouldn't have see even if I did
It's still a criminal offence to go through an amber light unless you can show that it was actually unsafe to stop. (I've driven over a million miles but I doubt that I've been through on amber more than a couple of dozen times). So the police don't need to show that the light was red anyway.
>>>why didn't they pull me over 14 miles earlier?
Possibly because they wanted to record your driving on their cameras, with a view to prosecuting you for other offences (such as driving without due care and attention, or dangerous driving) as well as for speeding. Or possibly because their control centre had told them that they might be required to assist at an incident somewhere else, so they couldn't stop you until they'd been released from other duties.
>>>when it gets sent off to the traffic offence department try could do me for dangerous driving?
While the CPS can review all evidence which is placed before them, and then institute or amend charges, the police normally indicate the highest level of offences which they believe is appropriate. It's unlikely that a 'dangerous driving' charge would result now.