Well I've seen the builders, spoken to the company owner and the offending plant operator.
I recorded the whole conversation and it was enlightening.
The owner said he heard a noise that "wasn't right" and that the plant operator just carried on working as if nothing had happened (probably hoping he'd gotten away with it) and when he went over and asked him if he had hit the car he said "yeah I think so". So something didn't fall on it, he hit it with the digger! But it was only a nick apparently.
To cut a long story short, I have an admittance of liability from the company owner and the guy who did it recorded.
The guy is going to get his "bodywork guy" to come and have a look and see if it's reparable, which I don't really think it is considering there are big hairline cracks that you can't see in the photos, one of which runs all the way to the front of the panel from the damage.
If it's repairble then he's going to foot the bill. If not, then his or the companies insurance will foot the cost as with the replacement panel (that only come in pairs) plus paint, plus a bonnet and paint, plus reblending it in to the skirts is a bill of around £4500 total.
The main thing is I have admittance on recording, and a promise of repair or insurance to cover it.
Oh and the guy has apparently owned a couple of Supras and it's alright because they are only worth about £3000 anyway according to him which made me chuckle a little. What a douche!