At first I thought it to be Vicia hybrida but after checking various painted illustrations and photographs, I realise that it cannot be. I am unsure whether it is a Vicia or a Lathyrus. The leaves of Lathyrus are nothing like those in these photographs. Appreciate help.
After checking further, there are two possibilities. These are Vicia grandifolia and, once again, Vicia hybrida. Remain hopeful that a member can help with ID.