Thanks everybody. I was told by my cousin Jay Farrell from Bohola in Co Mayo that Sean O Farrell had indeed existed .After he died his once relatively prosperous family from a small place utside of Longford became destitute and ended up in Bohola.

Jay wouldn´t say how he came to find this out only that he had checked through available records and had "other sources". He had originally heard about the connection through my grandmother , Katie Farrell.

When I said that he would be regarded as a hero if he did exist he said ,"dont you believe me he would be a hero to some people but not to everybody ."Not to the British, you mean," I said.
"No, not to the British but also not a hero for others."
It was then the penny dropped for me and I said "you mean not for his family" . To which he nodded his head.

I remember asking him at the time if it was some sort of a family secret He said "no ,not exactly a family secret but something that was not discussed in the family. (A family secret in other words I thought )

Jay was a member of the Conservative Party in Finchley , London at the time. My father told me that all of his family were Tories going right back to before the civil war in Ireland .