You haven't heard from us for a while because we've been mostly dealing with more mundane finishing of the house - things like painting and decorating etc. We held off having the final EPC assessment until we'd insulated the basement ceiling - the final part of the thermal envelope to be installed. This was done using a fairly conventional method: slabs of PIR (2x75mm thickness) inserted between the joists and then all edges taped.
Anyhow, with all the "eco" elements of the refurbishment having been completed, we recently got a revised energy performance assessment done. The surveyor was very impressed with the house, and said they couldn't think of anything else we could have done to it.
And the result is: a grade B (energy efficiency rating 86, environment impact rating 84).
I personally don't think that much of the EPC methodology, but we needed to use it because our mortgage lender Ecology Building Society set the interest rate dependent on it. A grade B was the optimistic end of our predictions, so we're very happy with this result. And because the project has overrun its budget, the reduction in borrowing cost is certainly needed!