A "grade 9" was also introduced in 2017, and that is higher than an A* [0], so some people refer to that as A* * (A star star) [1].

[0] https://ofqual.blog.gov.uk/2017/04/05/setting-grade-9-in-new...

[1] https://www.theguardian.com/education/shortcuts/2014/sep/14/...