Here are some photos of the tree over the past few weeks:
I recently found out that the yellow in the centre of the horse chestnut flower changes to pink after the flower has been pollinated. You can see the two different coloured flowers in the photo below. Bees can't see pink apparently, so they ignore the flowers once they change colour.
And here you can see the conkers starting to form at the bottom of the infloresence
and in fact now, some of the inflorescences are almost entirely devoid of flowers and well on the way to becoming conkers