Awesome Huw - the detail is amazing - did you use spot metering ? How heavily (or not) is that cropped?
I'm also assuming this is the 40-150 PRO and not the £150 lens ?
EDIT - centre weighted average and +1.3 ev.
EDIT 2 - answering my own questions here
I can see the MC-14 is dedicated to the 40-150 and 300mm PRO lenses and whe used the max aperture is a stop darker - hence the f4 and what confused me.
As an aside, I always think I am not really into telephoto lenses - the longest lens I have owned for any length of time was the O75 prime - I did buy a Panasonic 300mm zoom lens off of Marcia some years ago but didn't keep it long as I didn't use it and I also bought the Oly 40-150 portrait kit but only really for the little blue bag and sold the lens straight away..... but then I see shots like this and think WOW I need a telephoto lens - although I know I'd struggle to have the patience to capture a moving bird