The way Notes works, the first line is the name of the note. Normally the length of the first line would be limited, but when you paste it may create a first line that is very long. It sounds like you managed to copy a lot more than you intended to, and that has created a note with a long, possibly multiline name, full of code.
The weird thing was, because I had never used the BBC site before, I first cut and pasted the recipe into TextEdit -checked it for problems, then cut and pasted it into Notes which then triggered this problem

Try copying that text in the note and pasting it into TextExit.
Select Make Plain Text from the Format menu in TextEdit to remove any markup that may be lurking.
Done that

Then edit and remove the trash from above, below, and inside the recipe text, then copy that. Switch back to Notes, Select All to select the entire corrupted note, and paste over it. You may need to add a line of text at the top of the note if the entire recipe somehow has no line breaks in it.
I followed your direction but was not able to paste or add a line of text.

I had previously reset Safari to disallow open apps to reopen on start up, This allowed Notes to be opened, though it locked up if I tried to delete the Note self marked as ‘BBCadvert’, and had been unable to get past the corrupted note to do anything else.’

More out of desperation than anything else I shut down then restarted the computer - on the third attempt the corrupted note had disappeared, Safari no longer opened with two blank tabs, one named SafeFrame Container, one HTMLS local storage test, and I was able to delete the note marked ‘BBCadvert…’

I dislike Notes but have, until now, persevered with it but am pinning my hopes in this being a one time glitch.

Thank you for your help and patience
Kate

Edited by Kate (06/08/15 11:33 PM)

Last edited by alternaut; 06/09/15 12:56 PM. Reason: Fixed markup