Lessee: the top speed of a Royal Navy frigate in proper trim should be about 30 plus knots and the top speed of a supertankers is what - maybe 20 knots? Why didn’t the British frigate attempt to overtake and recapture the tanker?
The tanker was headed into the Gulf through the strait. It isn’t that wide. The tanker simply made a turn to starboard and was inside Iranian waters before the frigate could overtake (assuming it was even in a position to do so).
The IRG is desperately trying to start a shooting war.
Other sources suggest that the Montrose was 60 minutes away from being able to help.