Cricket,
We have only had two hours trading so far, you can also bet as with chesterone's comment there are trades being delayed that have not shown yet, since the trading statement we have only had 5 days where the volume topped a million and they all saw good rises. Today's rise is more to do with the MMs short position and how they have been trying to hold it back over the previous days by keeping the spread wide (yesterday's mid price should have been .75p higher than it was shown and that has magnified today's rise). The FDA decision is imminent if it is within the 90 day timeframe, so people are buying in ahead of that.
And all this in between Christmas and the New Year.