In Galloway.

The priory was founded c 1175 as a daughter of Soulseat (RICHARDSON AND WOOD).  Premonstratensian canons replaced either Black Canons (Austin) or secular clergy serving the cathedral.  It was a priory because its community formed the chapter of the cathedral.  In such cathedrals the bishop had been originally the abbot, with a prior as his 2IC;  when it ceased to be common to have a monk as bishop, the prior became the superior of the monastic community and was a very important person.  This was a rare arrangement, in which the Whithorn canons administered the cathedral and were deeply involved in diocesan affairs including electing the bishop, who needed their consent in many diocesan matters.  

Commendators:  in the 15th century non-monks began to be appointed as abbots, but had to become monks first;  this usually took place over a 2 year period;  until then they functioned as abbots but were called commendators.  Some commendators never became monks.  The Scots King and Pope agreed in 1487 that the Pope would wait 8 months for the King to nominate a new abbot;  in 1535 this was extended to 12 months.  There were abuses:  appointment of children as commendators until they were 22, when they became monks;  children appointed as commendators for life.

Priors:  there are gaps in the record and sometimes dates are approximate (DILWORTH).
1160s William, prior of Galloway.
1177 Michael, first Premonstratensian prior (RADFORD).
William Douglas Aug 1447 –1466, when he died;  he was the illegitimate son of the 5th Earl of Douglas.
Roger, prior in 1473.
Patrick Vaus 1478 till his resignation in 1503.
Henry McDowell, Vaus’ nephew, 1503 – Sep 1514 , when he died.
Cardinal of Cortona Oct 1516, but Governor Albany also nominated his illegitimate brother Alexander Stewart;  in Dec 1518 Albany changed to nominate Gavin Douglas, who bought off the others and was commendator in Jun 1520 until he was made archbishop of Glasgow in 1524.
May 1525 15 year-old Ninian Fleming was made commendator for life;  he took orders, which jeopardised his position but was supported against the claim of Abraham Vaus by the King, and remained as prior until his death in 1538.
On 2nd Jan 1539 the King nominated Malcolm Fleming, who also ruled the diocese between 1541 and 1559 as vicar-general.  Both the latter seem to have been good churchmen.