https://oneclickhangar.com/oneclickrepaint/share.php?id=bmkoelpV1OMK9TRFjddgA fairly old unpressurized retractable C210T (Turbo Centurion, the fastest ones in the Roman Army) privately operated out of Thurrock airfield (EGMT) in Essex, UK.
Despite a drought of recent images, this one still operates. The last flight was a round-trip of the Kent coastline, with a small orbit in the vicinity of Dover, for sightseeing purposes. If all it does is "trips round the bay" from a less-visited airfield in Essex, that might explain a recent lack of sightings.
https://www.jetphotos.com/photo/9915624