I caught a few of the streaky grey and white Coleophora in the garden over the summer, and kept a few for dissection as this group is more or less impossible to ID externally (with a few exceptions). I've now dissected these and the results are:
Coleophora tamesis 5 (foodplant: Jointed Rush)
Coleophora glaucicolella 1 (various rushes)
Coleophora striatipennella 1 (stitchworts and mouse-ears)
The predominance of tamesis is suprising as I don't know of any Jointed Rush around Llandaff North. C striatipennella appears to be only the 6th county record, though there is a previous one from ST17 (Penylan, 1989).