Today those lovely, nay indispensible, people at Chilterns Seeds delivered packets of fun from Rhododendrons at Muncaster Castle in the Lake District, the seeds having been collected from the original specimens planted there from collections made in the Far East in the late 18th century by such luminaries as Forrest and Kingdon Ward.
I went for R. yunnanense on the premise that it is a very common parent in modern hybrids and this somehow led my mind to believe they might be quite easy from seed (I have never previously succeeded in raising Rhododendrons from seed). And added griersonianum cos it sounded nice, hyperythrum and floccigerum because I'd never heard of them and it's nice to have stuff other people don't, even if it's just a scabby Rhododendron clinging to life on an East London rooftop. So they went straight on to the surface of a peat-based mix with rotted bark and vermiculite, covered with a light sprinkling of vermiculite and put in the sealed, humid, cloche to catch the last of the autumn heat before possibly coming out for a good freeze in December before going in again in Feb/March. Might work, probably won't.