I’d say that once that socket is screwed back, it’s all earthed back through the SWA as it’s a metal back box.
Not something I’d rely on but with two fixed lugs on the back box, would that not technically comply?
If it were my job, I’d add a 2.5mm fly lead on that end though, and for the plastic back box, just swap the lock ring over for one of these and just attach another flylead.
https://www.NoLinkingToThis/p/earth..._WtAJX7X4y5YWR-XzRkaApI9EALw_wcB&gclsrc=aw.ds
Should take you around 10-15 mins.