Seems like a very well executed combined FON and media op.
In March / April that nice Mr Putin unilaterally declared an exclusion zone in the Black Sea contrary to the provisions of UNCLOS.
HMS Defender leaves Odessa to transit to Georgia, including innocent passage through Ukrainian (Crimean) territorial waters, as permitted by UNCLOS.
Russia puts out media blast "Rodina stronk - warship chased away with live fire after violating Russian waters".
UK MoD - calm statement, ship was not fired upon, normal passage etc.
Followed up by BBC correspondent on the ship, noting that ship didn't deviate, despite lots of Russian buzzing and that she intended to follow that course.
Message delivered. Contest Russian actions iaw NSS.
Sod off Sergei.