Collared Pratincoles - ?? Bosherston/St Govan's

Message earlier from Matt Sutton followed up by a phone conversation this evening, Matt had two (!) probable (Collared) Pratincoles over Mere Pool Valley, Bosherston, late morning today.  Unfortunately he was without optics due to doing a fauna survey, but watched the birds hawking insects high over the valley before heading of the in the direction of St. Govan's Head.  The shape/jizz could only have been a Pratincole species, and on listening to calls this evening (Matt was first alerted by a bird calling) it closely matches the call of Collared.  Matt is an experienced birder but clearly didn't get enough to be 100% sure, but sounds like the 2 that got away....unless they are still around somewhere??  How about Castlemartin Corse or Frainslake? Apologies for the late posting but this is my first chance to post after speaking with Matt.