Thanks Simon and McCreed for your replies,
I'll try and remember to try more post wraps when adding strings.

There is quite a decent break angle from the nut to the tuners.

The E, A and D strings seem quite flat in the nut, so I will try to angle the slots down to the same angle of the headstock. I have the needle type nut files (a good set is on my wish list - but it is a looooong list!)

If this does not work I will look into a bone nut.

In the meantime, placing my capo across the headstock and strings fixes the problem. Maybe this is a convenient place to store the capo so that it is always on hand