Andy Burns wrote:

There are battery schemes within the national grid's "enhanced frequency
regulation" scheme, not found yet whether this one does

Apparently, yes is is ...

"Clay Hill will bid for revenue streams from various tenders €“ both
Enhanced and Fast Frequency Response, and the Capacity Market €“ when ready."

https://www.solarpowerportal.co.uk/blogs/inside_clay_hill_the_uks_first_subsidy_free_solar_ farm