On Wednesday 22nd...
...this (coming) Friday is the 24th
...next Friday is the 31st
...last Friday was the 17th
...Friday last would also be the 17th


The confusion arises from the failure of anyone to mention that "... last" or "... next" is Northern English shorthand for "... last week", "... next week."


So, in the examples above, "this Friday" and "next Friday would be the same date, (24th) but Friday next would, indeed, be the 31st.
"last Friday" and Friday last" would be the same, in that example (the 17th)

In Faldage's example (many posts back), if today is Saturday, then the day before would not be "Friday last" - that would be refering to a week previously (using the doc's example, it would be the 10th) - but, in any case (as someone pointed out - dody, I think) the day before would always be refered to as "yesterday", without fail unless someone was trying to be purposfully stupid.

Has that troubled the oily waters sufficiently?