So the modellers at Imperial have released a new paper:
www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-Europe-estimates-and-NPI-impact-30-03-2020.pdf
The really interesting part is the table on page 6 which estimates the infected population (and a 95% Confidence Interval) with the mean at 2.7%.
That would mean somewhere approaching 200,000 are infected, compared to the actual number of identified cases is around 22,000.
Remember this is just a model, with lots of caveats, but based on lots of emerging data. If so, it means the mortality rate is likely to be a lot lower than previously thought - even taking into the account the lag effect of reported deaths.
Interesting reading nonetheless.