Pelargonium Coriandrifolium?

I have neither the experience, knowledge or background to examine a Pelargonium and accurately identify this Pelargonium.  I have written several times about a lovely plant which I bought from Stourhead nearly three years ago.  Earlier this year, I joined the IGC and the Geraniaceaa Facebook Page.  There Elena Loganson cast doubts on the original identification saying that the plant "Looks like P longicaule var longicaule, and not P myrrhifoloim v. coriandrifolium, because of the long hypanthium and leaves, which have a width of segments greater than 1-2mm."

Of course identification can be tricky, and really the actual specimen would be required. In my search, regarding one of my summer dormant geraniums,  I discovered the Honorary President of The Hardy Geranium Group of HPS, may be able to help me understand the differences in this Pelargonium.  

David has gently introduced me to some of the anatomy of the Pelargonium, and that explained that there are subtle differences between different plants:

"Unlike most genera, the nectary tube on Pelargoniums are external to the flower stalk, as is the nectary itself.  The latter is normally quite clearly seen as a small lump on the flower stem and, if you look carefully, you will also see the tube leading to it from the centre of the flower.  In Pelargonium this is a key characteristic e.g. there are some sub-species which are separated from one another by the differing lengths of the hypanthium.  The important measurement is that from the back of the flower to the centre of the nectary.  In many species, there will be a bend in the flower stem at the nectary.

I should add that the term "hypanthium" is technically not quite correct.  However, it is the term that is almost exclusively used."

David Victor's interest and knowledge in the Geraniaceae is well known. He is involved with a number of societies and groups, and was Chair of the International Geraniaceae Group, the British Clematis Society, the Hardy Geranium Group and the Peony Group of the HPS and deputy chair of the South African Bulb Group and International Cultivar Registrar for Geraniums. He still keeps his National Collection of Pelargonium.

I have now propagated another generation from cuttings, and hopefully next year, with his expertise, we may be much closer to confirming its identity.  

Last year's cutting in flower in June.  The flowers have been removed, and the plant continues to grow well.