I remember you posting when you first had it!
WTF can't people sip a beer at home or get a professional to take them home for the price of an additional two beers, which clearly they had well more over the limit of?
That looked like a well-looked after car and being a diesel, it won't surprise my if the insurance people assess it well under its actual worth! In my experience, I would suggest you clean it before they come, hoover, wash, etc making it look as pristine as possible prior to the accident as I am really sure they knock down every little flaw they can, in order to suggest it it worth less.
It will almost certainly be the third parties insurer doing this as they want to lower any payment and I recon they are under guidelines to scrap diesels or reduce their values in order to reduce them on the road bit, by bit!
The better the wreck looks, the higher the opinion of the car will be. I had mine quite dirty as it was parked up for a air few weeks, and had an old vinyl roof sticker, to protect the paintwork from a roof box but I think they looked at that as damaged paint and not protection (?) along with scratched wheels, etc that are really quite simple to renovate or even swap. When it came to having a new battery, an engine with 50,000 miles less then the clock stated, genuine arm rest, many dealer extras, they were overlooked with a statement of they don't add anything after a cession period of time and the engine no longer ad a warranty on it so the rest of the car had travelled that distance... They stab your back with the bad things and don't even offer a plaster, when you point out the good things.
This was despite my argument that the lower mileage engine and all the extras, made the car more desirable when offered for sale and harder to replace, like-for-like, which is what is supposed to be offered.
That said, they well over estimated the cost of repair so when they paid me the (low-ish) value, I had it fixed and had the wheels painted along with a few small dints and it looked better afterward and I made a few quid! (I only had a dented passenger door and broken mirror, which they then said wrote the car off).