Car written off, now for sale again?

As per the title, someone pointed me in the direction of a donedeal ad for a dealer selling a car that I previously owned.

Now the issue is that the car was written off in a reasonably big rear end smash about 6 yrs ago. I was stopped and a guy ran into me at about 45 - 50 mph, enough to smash the rear end in, crease the roof, prevent the rear doors from being opened and bent sections of the rear chassis. It was a big, reputedly strong car, which I loved at the time.

I rang the dealer to confirm the reg as it was blanked out in the ad (but visible in the NCT cert picture) and then advised him it had previously been written off by the insurance. He has said Cartell have given it the all clear and it has a NCT cert, as noted above.

Now I know it is common enough for write offs (especially economical ones) to return to the roads, but I was with the mechanics is the brand dealership when they were looking at it after the crash - it was up on the ramp, and they were saying that it should never get back on the road.

Question is, what should I do? I would feel bad if someone bought it in innocence not knowing the history, I sure as hell would not like it done to me.