Well I finally got around to getting a new vapouriser and it's burning perfectly now.
Once it warmed up I did a test run, I weighed it, 30 minutes later I weighed it again and it was exactly 30g lighter. So assuming the density of paraffin being 0.9g/cm3 then that's 66.666ml/h (recurring). The tilley tank is 1.5 pints, so near as dammit 850ml, taking the rate of fuel use that should give me 12.75 hours of run time on a full tank.
From what I've read that's quite respectable, I'm happy with that