Car is a write off, no question about it. However, all 3 cars involved are insured with the same insurer, and it looks like this may get the claim settled quickly. Also, reading through the paperwork of my original purchase, I discovered that they had thrown in GAP insurance cover, which should top up my insurance to the original purchase price.
Meanwhile, I have discovered that the showroom where I originally bought the car has a similar model, albeit with slightly better features, available as an ex-demo. Once I know that the insurance is going to pay, I plan to move on that; rather than wait for the payout, as it is too good a bargain to miss.