Hi Dan@AdrianFlux

Quick update on this. I renewed my Agreed Value insurance at an agreed price last year, then got the paperwork asking for another £15. Called to complain and got it waived.
Renewed the policy again this year, asking THREE times to confirm the price included the Agreed Value, and paid in full. Then the paperwork comes in asking for another £15. Called and got that waived AGAIN.
Then I get an email saying the pics and Agreed Value form are being sent for approval and in the meantime I'll be covered on a normal basis. That's not what I bought so I called but I'm not allowed to speak to the Agreed Value team and have no idea when they might get around to agreeing (or not) my valuation and I'm not about to go outside the 14-day cooling off period in the hope that they respond in time.
Anyway, I can't be bothered with this dance every year, so I've cancelled the renewal, await the refund and will take my business elsewhere.

Now looking for recommendations for anyone competent to cover modified cars.