Hey guys, for what it's worth, I'll post up my findings here in case if helps anybody in the future.
I kind of always had an oil consumption issue on this motor since I had it running last autumn. This spring however, it had gotten worse and I was getting wet plugs. Clutching at straws, I replaced the valve seals...no improvement.
Tore down the block and sure enough the piston rings weren't fitted properly. My motor has a special support/spacer ring that sits amongst the oil control rings (only Lord knows why) and the builder didn't know what to do with them, so he didn't fit them.
My bores were chewed up from the wayward piston rings and in some places down low, you can still see where the rings dug into the bores due to the excess clearance.
That's where my filings were coming from - just thought I'd share.