Permalinks not working for me at all

I have the normal links – and the permalinks modules installed

In this page – http://natureslens.co.uk/2014/03/japanese-winter-wildlife-photography-tour/ – both the links are pointing at the same post – the one via ID works – the one via permalink does not

Permalinks are set to month date, nothing custom in there to confuse the issue

Very odd

https://wordpress.org/plugins/modal-permalinks/