Seen by a hedgerow nearby as well, although this one was at the base of a bus-shelter.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
Definitely P. lagenophorae. What we see are the aecia, or "cluster cups", of the rust. This introduced species is now common on Groundsel and Oxford Ragwort, and occurs also on the rapidly spreading alien, Senecio inaequidens.
Another bright orange rust occurs quite commonly on Groundsel - Coleosporium tussilaginis - which produces more amorphous sporing stages. I have seen both rusts on a single plant - which didn't look very well.
I am not familiar with this gall, but until I saw Alan's comment I was going to suggest that it is C. tussilaginis. This is because the observation mentions reddish tinges. The other difference between them is that P. lag causes much bigger swellings on stems and leaves than C. tuss.
In view of Alan's comment I am not so confident!
Lat/Lng: 50.9, -1.4
OS grid ref: SU4619