After your first reply I went and cleaned it all up and the gunk is not greasy and it does smell of tyre. And looking at the diagram you posted its looking like it is a tyre weld sealant thingy.
Thank you very much.
Just got back. Limped home with a flat tyre. Also when I had a look there was lots of gray gunk over the rear mudguard. It leaked from the spring preload adjuster.
Has anyone had this happen and also where do I refil the fluid.