Series 3 Oil Debris

I'm was preparing to fit a new oil pump (https://www.landyzone.co.uk/land-rover/oil-pressure-light-spookyness.332578/) and noticed a layer of greasy grit (i'm guessing carbon deposit) in the bore that the oil pump fits into. I've checked around the crank and in the tappet gallery but can't find it anywhere else. It just seems to be in this area where the pump slides into place.

I've been trying to clean it out but after 3 hours of white spirit and a tooth brush it I feel like someone keeps adding it back in while me back is turned.

I guess my question is; is it harmful, does it need to be cleaned out (given that it is before the oil filter) and what will shift it?

bottle brush and paraffin or petrol etc

and it all must go? I'm guess the answer is "yes" but i'm really hoping for cheery "no"

no, its just best practice to remove as much of any deposits as possible

Thank you @jamesmartin . I'll give it another hour and call it quits.

Blunt screwdriver?