Hundreds of these aphids like insects are on my neighbours fir tree. He is very keen to know what they are and if they are harmful.
No interactions present.
these could be
Black bean aphid
familiar garden "blackfly" usually on beans, sugar beet etc
It looks like some of the ones on this page -
It's not Aphis fabae.
It looks very like Cinara piceae. That lives on Picea (spruce), not fir. Assuming the neighbour's tree was indeed spruce, this is a fairly definite ID.
Lat/Lng: 52.7107, -0.3593
OS grid ref: TF109138