As it was cooking there seemed to be a huge bubble rising in it. I thought that despite pricking the base of the pastry before adding the jam and then the almond filling that the problem was my pastry but on slicing the tart, it seem that there is simply an air bubble, because i thing the pastry looks ok. It seems crisp and crumbly and looks cooked on the bottom too.
The problem with this recipe is that as i really dislike almonds which means i've never had a bakewell tart so i'm not too sure what it should be like! Hopefully my taste testers at D's work will pass on some feedback.