Paul, Searching your walks, I noticed that some have there difficulty rating missing from the initial results page, eg https://www.walklakes.co.uk/walks/tag/8 the top 10 are blank.
D'oh, it looks like that bug has been there ever since we automated overall walk ratings (which we did a very long time ago). I'm amazed no one's spotted it before, either on our side or the users.
Anyway it's lucky someone was paying attention so thank you for the report. Now fixed.