Thanks, Aghadowey...
One other point. The brother, Peter (and this is as I understand it: I can't confirm the details) had been employed in the building trade, like so many other Irish workers after WWII and, especially, during the 1950s. It doesn't preclude education, of course; but how is it that TD, the sister, got herself a job with BOAR? She spoke (I know this) fluent French and German and was, according to other information, actually working in a branch of British Intelligence before her posting to RAF Gatow, just outside Berlin, in 1946. Can we account for her education, then, in a family that might look, on the surface, to be centred in a primarily rural economy - and, so Peter's occupation implies, not well off?
Onwards and Sideways, then.
roly