If you freely admit you would routinely undertake a vehicle travelling slower than you, you probably did it.
Can you point out where the OP freely admitted to routinely undertaking other vehicles? I seem to have missed that bit.
“the offence described just doesn't sound like something I would have done, especially as I am aware of the stopping abilities of my 3 ton vehicle and I would assume that the vehicle in question was an unmarked police car.”
Maybe freely admit is a bit of a stretch but the op didn’t say they didn’t undertake. I read this as the OP saying it must have been an unmarked car as they would remember undertaking a police car and due to the size of their vehicle they wouldn’t leave it too late ti change lanes.
Of course they could have been saying they never undertake as they always drive as if every other vehicle on the road is an unmarked cop car.
Either way unless the OP now thinks it’s a case of mistaken identity that they can clear up before it gets to court (ie it wasn’t their van at that location at that time) it will probably be cheaper to do the course.
I think you're making a few too many assumptions here - my post is not about admitting or denying any offence - it's about the possibilities of getting what I would call "Proper evidence" - not just a vague 2 sentence explanation that doesn't provide enough information.
My remark about it being an unmarked police car simply means that had I approached a marked police vehicle at speed, I would have very clearly seen it and remembered doing it - more to the point, if anyone decides to approach a marked police vehicle from the rear (or otherwise) at speed, they deserve what they get.
Also there's no mention of mistaken identity in my post???
To reiterate, my post is not about me being guilty or innocent - I have enough of a moral grounding to admit my wrongdoings if that is indeed the case - at this moment, I do not consider that what little evidence has been provided is enough to verify that the offence took place and would like more.
It may have been a case of me driving as they have claimed, I find it hard to believe but maybe I did commit the offence that they have stated but for whatever reason, I have no recollection of it. If I am provided further evidence (video evidence) that clearly shows me driving without due care and attention, I won't be making any efforts to try and convince anyone otherwise - however I am not willing to pay a fine, receive penalty points etc on the basis of the information I have so far.