Its a fail & it must be a fail if theres nothing on the paper or utter gibberish
If theres something on the paper paraphrasing & embroidering the words of the question, that is a clear pass
If they try to unpick the question to see what its after, thats a Lower Second
If they make a stab at answering it with a lot in it you can understand, thats an Upper Second
And if they make a stab at answering it at considerable length with a lot in it you cant understand, thats almost certainly a First
Professor Smellies briefing to new examiners, quoted by Bernard Crick in My LSE
Nowadays 52% of LSE graduates get a 1 or 2.1, or so I read in The Times. In the 1960s there were some years when no Firsts at all were awarded in some subjects