I'm sorry but I still don't get the whole Jewish thing. He was interrupted by people who happened to be Jewish but was there something specific related to Jews that caused them to interrupt him? He could have just as easily been interrupted by Gentiles. And if he was enraged at the Jews the GSG really doesn't seem to reflect that but comes across more as a mild rebuke. Hardly worth taking a chance to write.
The simplest explanation is that the (apparently) anti-semitic graffiti was already there before the Ripper jettisoned the apron.
Hi Sam, trust the skies over Wales are still full of dragons and sunshine today.
In isolation, yours is a not unreasonable observation, but in the context of the evening's other events (and the series moreover), your very sensible interpretation is reduced to one more co-incidence in a series of co-incidences. And please keep in mind the issue of blame which is the active thematic of the missive: blame for the murders - and I believe, a reference to the anti-Semitic rioters with their chant of "no Englishman" post-Chapman, who had blamed the Jews.
As Reid it (probably) was, who so aptly put it, in 1889:
“He lives in Whitechapel, of that I am confident. His knowledge of the locality is astonishing". Indeed, JTR well knew his neighbourhood's raw nerves and exposed sinews - even if he had to dirty his hands to expose them himself, literally.
PS - the 'already there' interpretation, may also need to overturn Long & Halse .
I've mentioned this before but if the message was written by Jack (and no we can't know either way) could he have written it directly after leaving Berner Street? Maybe he stopped for a fag to try and calm down after being interrupted in his work? Maybe he got even more angry? Maybe he wrote the message in anger? Maybe later he felt angry that his 'message' might go unnoticed so he decided to leave the cloth as a 'signpost'? Maybe this explains the time gap? Depositing the cloth was an after thought?
Sorry about the 'maybe' overload there chaps
"There is nothing more deceptive than an obvious fact!"