Whatever the circumstances of their introduction, Graham Greene's future mistress Catherine Walston (their affair began in 1947, according to William Cash) and her husband Harry Walston certainly stayed with Ernie and Elen O'Malley at Burrishoole, and the two couples reciprocated visits regularly.
According to Cash, Catherine Walston was 'almost certainly' having an affair with Ernie O'Malley up to and even including the time she also became involved with Graham Greene. Locals on Achill old enough to remember the elegant American Catherine Walston and her old petrol-hungry Ford car recall her usual companion as the local ladies man O'Malley rather than the tall, suave Englishman Graham Greene. Walston and O'Malley would often stay up late drinking whiskey at the bar of the Clew Bay Hotel ('Gielty's') just opposite her cottage in Dooagh. Greene is remembered as a quiet man, presumed to be taking 'writing holidays', and who was a poor bar billiards player in The Pub ('Lourdies') in Dooagh.
It is likely that Greene and O'Malley would have met at this time, through Walston and her social circle, but equally likely that neither would have known about each other's true relationship with the American. Indeed, early in her affair with Greene, Catherine Walston asked him to use his extensive literary connections in London to secure introductions for Ernie O'Malley, who was visiting England as poetry editor of the Dublin literary magazine, The Bell.
Commentators frequently observe about Graham Greene's work that it has a very religious aspect to it. Greene himself, despite his adultery (Catherine Walston was only one of a number of mistresses), was a committed Catholic. His circle of friends included many Catholic priests as well as the English 'Catholic-literary-mafia' that included Evelyn Waugh and T.S. Eliot. He was introduced to Catherine Walston shortly after her conversion to Catholicism in 1946 (Cash claims that Walston's conversion was due to the influence of Ernie O'Malley) and it appears that religion - and particularly Catholic notions of guilt and sin - were to feature strongly in their relationship. The following verse, part of a love poem ('After Two Years') written by Graham Greene to Catherine Walston, was quoted by Cash as evidence of the significance of Achill Island to their affair:
In a plane your hair was blown,
And in an island the old car
Lingered from inn to inn,
Like a fly on a map.
A mattress was spread on a cottage floor
And a door closed on a world, but another door
Opened, and I was far
From the old world sadly known
Where the fruitless seeds were sown,
And they called that virtue and this sin
Did I ever love God before I knew the place
I rest in now, now with my hand
Set in stone, never to move?
For this is love, and this I love,
And even my God is here.