Ordinary insurance pays what a car is worth on the day of a claim. For a classic, that can be far less than what you would need to replace it.
Agreed value
With an agreed-value policy, you and the insurer set the car's value when you take out the cover. If it is written off, that is what you are paid.
What it costs
Classic policies are often cheaper than everyday cover, because the cars are driven less and looked after well. Limited mileage and a garage are usually required.
Keep it up to date
Classic prices move. Review the agreed value every year or two, with photos and receipts for any work done.
Before you buy
Get a quote before you agree a price. Some models cost much more to insure, and it is better to know that first.

On “Insuring a classic: agreed value explained”.
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