Are Welsh Waters a haven for Sharks?

A Dutch lady popped into the Ocean Lab to report a Thresher Shark sighting from their boat  as they sailed past Anglesey, just off Treaddur Bay on the 16th of July. Her English was limited but the description of this big  long tailed shark breaching was unmistakable.
This is the fifth sighting that I am aware of in the last three years in Welsh waters including the one Rich Crossen Photographed off South Pembrokeshire in August 2013.
Considering the fact that there are very few previous records in Wales and sightings around the UK are few and far between this may well be significant