...and having tapped in a 'soap Roget gallet kidney' google images search...this image looks vaguely familiar:

 

I remember now...the CID were to mention that janina had left 'white cakes of soap' in that Martello tower...along with 'the usual'...well I would guess that it had been all about that Sephardic curse upon the Ashkenazim in relation to the Nazis....and as far as I know...from information relayed on...she as to call those oval cakes of soap 'white kidneys'....go figure....