this response is very gratifying - thanks everyone
this one is very common and should be fairly easily found by anyone looking at the hosts - Puccinia lagenophorae
It was originally described by M.C. Cooke from leaves of Lagenophora
collected at Omeo, a small historic gold-mining pioneering town on the edge of the Snowy Mountains in Victoria, Australia. It was unknown in Europe until its discovery in 1961. In that year it turned up in France and was discovered by Dr R.W.G. Dennis of Kew at Dungeness in Kent. By the following year it was found in SW England from Sothampton to the Lizard, in Wales and in the Scillies. It is unlikely that such a striking fungus had been overlooked before that time.
In Britain and Ireland it is very common on Senecio squalidus
(Oxford Ragwort) and Senecio vulgaris
(Common Groundsel - including the latter’s radiate form); it is very rare on Senecio cambrensis
(1 record?) and has been recorded (again rarely), on a number of related species in other genera but we don’t need to go there in what is intended to be an introduction to this area.
There is another rust which attacks Oxford Ragwort and Common Groundsel, Coleosporium tussilaginis
but that never has the “cluster-cups” which can be seen here, with their pale outer rings; it forms more shapeless areas of attack, and in addition it tends to occur chiefly on the underside of the leaves. P. lagenophorae
sometimes attacks its host so successfully that it becomes a contorted mass of stems and leaves:
best wishes and good hunting