Here we go.... I had another look at the genealogies, determined this time to figure the thing out.
Barbara Cartland married firstly
Alexander George McCorquodale (son of
Alexander Cowan McCorquodale) and had daughter
Raine.
Barbara Cartland married secondly
Hugh McCorquodale and had sons
Ian and
Glen.
*
Hugh is the son of
Harold McCorquodale, brother of
Alexander Cowan McCorquodale. Therefore, Hugh and Alexander, Babs Cartland's two husbands, were first cousins.
Neil McCorquodale is the son of
Alastair McCorquodale and
Rosemary Sybil Turnor. Neil has one sibling, a sister,
Sarah a/k/a Sally van Cutsem since her marriage to
Geoffrey van Cutsem in 1969. Through Rosemary, Neil and Sally are great-grandchildren of the 13th Earl of Westmorland.
Neil's father,
Kenneth McCorquodale was brother of
Hugh McCorquodale being the eldest born (Hugh the third born) of Harold. So Neil is nephew of Babs Cartland's second husband, and Neil would be second cousin of
Alexander Cowan McCorquodale. This makes Neil and Raine related twice.
One the one hand, they are third cousins. But Neil is first cousin of Raine's half-brothers.
The links will direct you to the Peerage website which guided me through this web of confusion.
*Geoffrey van Cutsem, I now learn, is brother of Hugh van Cutsem, who married Emilie and then sired the famous van Cutsem brothers.