** British precision engineer Renishaw up c7 pct and top gainer on the FTSE 250 index in robust volume
** Co cuts FY rev forecast but keeps PBT forecast, causing Investec analyst Michael Blogg to say that "margins must be better"
** Margins a closely-watched metric for industrials as bottom-line generally represents only a fraction of the top-line number due to huge operating expenses
** Co cites difficulty in predicting large orders this year for rev cut; Its large order wins in the past linked to the launch of new products from Apple Inc
** Strength of the global smartphone market called into question this year, with companies hinting at weaker demand particularly from China
** Renishaw's stock has lost c.5 pct in value since July 28, the day before it first forecast lower FY revenue
** About 6X 30-day avg volume traded through in 5.5 hrs (RM: firstname.lastname@example.org)