Spot on the NAV figure. What I am puzzled about is that they don't say anything about the deferred tax asset.
In the last accounts they put a figure of £23m (I think). Not sure what % is recoverable but reading today's results they mention twice that there is no tax payable due to previous years losses.
So if 50% of it is recoverable (and the recoverable life of these things is about 20 years) we are talking about 1.6p on top of the 2.5p!