Right - i've now cured the oil loss by fitting another breather unit to it off a mk5 escort cvh. Slightly different design to the original, and this one isn't blocked like mine appeared to be.
It's now blowing a fine mist into the smaller breather on the inlet (rather than that fine mist condensing in the old breather, then piddling out of the airbox).

It no longer piddles oil and the engine feels perky again (however this may just be in my mind... )

But when i take the oil cap off when its running, you can tell it's breathing heavy...

Gonna get my mates compression tester on the go in the coming days to see if the rings have had it.