Checking on those 'POSSIBLES'

In a recent podcast Greg and Martha mentioned 'possibles' and wondered whether this is a term used in Britain. Aged 44 and lived in Britain all my life - I have never heard it. I have lived in the North East, North West, South West, East Anglia and I have worked with older people and all ages. I did a little vox pop and drew a blank also. Perhaps it is more an Irish term? PS Thanks for the fabulous programmes.