I’ve just discovered a Wikipedia page which seeks to record all the main leader ratings from the leading pollsters. The page describes itself as being confined to “approval ratings” which it doesn’t. Instead we see a range of four or five different formats.
Unfortunately the page isn’t quite as comprehensive as it suggests and I have had to add to the polls covered in my version of the spreadsheet above of 2018 ratings for Mr Corbyn.
The trend for the year is clear and there has been a marked negative movement for the current Labour leader since January. The latest numbers from YouGov have him at his lowest level since GE17.