Argyll's point illustrates the real dilemma with this scenario. I agree that perhaps the first vehicle making the left needs to be in the intersection (i.e. to pull up to see the live lanes if cars are blocking his view), but the red pickup was in the wrong. He should have waited at the stop bar and only proceeded in to intersection once it was his turn and the intersection was clear. Unfortunately, people crowd the intersection trying to beat the amber light to make a left turn.
This is why OP's situation is much more complicated that perhaps he understands. After all, there are several potential HTA offences at play: 1) by him; 2) by the vehicle struck; and 3) by the red truck in the intersection. The fault rules do not take in to account all those factors and therefore, do not answer the fault determination questions fully. If anything, he may get lucky with a 50-50 determination since the insurers will likely rely upon rule 15(3): where it cannot be established whether the driver of either automobile failed to obey a traffic signal, the driver of each automobile shall be deemed to be 50 per cent at fault for the incident.
Here's where the legal problem arises--CAN they establish an automobile failed to obey a traffic signal---certainly the red truck did (but he's not involved), the caravan involved in the collision MAY have failed to obey the amber but that's not definitive, and then there's OP. He failed to yield at the intersection, but did he 'fail to obey a traffic signal' when his light was green? From a legal perspective, there could be 2 arguments to that. On one side, it can be argued that section 144 is a complete section that deals with traffic control signals---and section 144(8) (fail to yield) is part of the elements to obeying a traffic signal. Thus, even if you follow 144(12) and can proceed on the green light, another element is subsection 8 of the same section that ALSO requires you to yield. The flip side to the argument is that each action is separate and, at least for the fault determination rules, he IS obeying the traffic signal (i.e. proceeding when on a green)---even though he failed to yield (but that's not part of the 'traffic signal' rules). I know its confusing, but hopefully I've made it clear enough.
That is why I repeatedly state the same thing-----this is a very difficult situation to properly assess. I would be VERY surprised if Op was held to be at no-fault. More than likely, the insurers will agree to just use the fault rules and go 50-50 (so as to avoid going to court). However, if this claim was for much higher amounts----undoubtely the courts would have to assess it all based upon the rules of tort law and factor in such concepts as 'forseeability' and conduct a 'causation' analysis---primarily using the 'but for' test. That's where OP could see his biggest issue.
After all, 'but for' OP proceeding through the intersection (when he knew or ought to have known) the intersection wasn't clear, the accident would not have occurred. Had he simply waited, the other vehicles would have been able to finalize their movements (even though they may have entered the intersection unlawfully). So, that's where OP seems to be naive. He seems to believe that because the caravan that collides with him disobeyed the amber (or failed to stop for the red) that he is absolved of liability----he likely will not be because that's a difficult determination to make based upon the video.
It would be wonderful if the fault determination rules answered everything---but they simply can't include all possible scenarios. When they don't, the fall back system is tort law analysis by the courts.
I think the debate rests upon some folks only analyzing this scenario based upon traffic offences that may have occurred. However, that doesn't necessarily translate into tort liability. After all, it appears that none of the parties is entirely with 'clean hands'. The court would therefore need to go deeper in to its analysis. If that happens, I think the court will likely go 60-50 to 75-25 against the OP----because no matter how you cut it----had he not proceeded through the intersection when he knew it wasn't clear, all of the losses could have been avoided.
Had there been a group of kids in the middle of the intersection, I think a lot of people would be able to see the legal concepts at play. Yes, the kids should not have been in the intersection, but if OP didn't proceed (when he had full opportunity to not do so) none of the losses would have occurred (i.e. the 'but for' test).
As some have said, this is a wonderful academic scenario and much more complicated than what initially appears. However, from a practical perspective, I think Op will be very lucky if the insurers agree the other driver is 100% at fault (for failing to obey the amber). More than likely, they won't be able to agree and will default back down to the 50-50 rule of 15(3).