To achieve what?
What are you hoping to do about this?
On the face of it, you seem to accept crossing the white line?
The law requires you to stop before the white line unless the white line is so badly broken that it cannot be seen in which case the law requires you to stop at the traffic light.
Plead guilty. You do not have a defence.
I'm very sorry but the law of road traffic is of strict liability and there is no defence in saying you did not know.
Can I clarify anything for you?
Is it charged as S36 RTA or driving without due care and attention?
That is S36 RTA.
If it is 7 seconds after then they could prosecute it as a driving without due care.
There is no way around complying with the S172 request. If you do not they will charge you with failing to identify which carries 6 points and a much higher fine.
You can mitigate on that basis on the court forms.
They may offer you the fixed penalty though.
All the best.
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