Maria
I have a feeling it was because it was a company car, that was the reason behind the delay. Whether I would have many rights as I didn't do a check myself when I bought the car, I don't know. Autocheck won't tell me or the buyer who the other insurance company is either, so I don't know how far I could push the issue.
The buyer has come back to me with an offer of 4K which I've rejected and gone back with a counter offer of 4.5K. I won't go lower, the only reason I'm entertaining this at all is because I feel bad for the buyer and because my wife is due to pick up her new car on Wednesday on condition of this sale.