@AandM56
I understand why you are upset, but Airbnb has gone ahead with the Superhost review, so they're not going to change that now I think. Maybe it might be considered in three months time.
However, they did announce some time ago that they were introducing tools to detect 'outlier' reviews: https://community.withairbnb.com/t5/Airbnb-Updates/Airbnb-Answers-Protecting-you-from-one-off-bad-re...
While the details here talk more about a guest leaving 5 stars in most categories and then a low score overall, if all of your hundreds of reviews are 4 and 5 star, then surely that guest that gave you 1 star qualifies as an outlier? The fact that he never stayed should support that assertion. Also, if you have evidence in the message thread that the guest was trying to get a refund and the review was retaliatory, that should booster your case.
I would therefore contact Airbnb and ask them to examine this review as an outlier and have it, and the associated ratings, removed. If they are willing to do that, it should push you back to Superhost level and you should also ask them to reinstate your status.
The problem is, right now, dealing with Airbnb CS is a nightmare due to all the cancellations and confusing policies about them. So, this might take a while, but I would definitely give it a go.
The only upshot is that, not being a Superhost, you don't get through to the 'Superhost Hotline'. Why might that be an advantage? Well, because you are in the UK, so if you call during office hours, you are quite likely to get through to the Irish call centre where the staff are very helpful and clued up.
Now, last time I called, you could not get through at all via the phone, and I don't know if the Irish call centre is even operating right now, so you might have to send a message instead, in which case it's the luck of the drawer whether you will get a sympathetic CS rep or not.