Having collected a good handful of another type of lichen ( upper moorland) I thought I'd have another go and see what happened this time.
I haven't yet identified it positively but it seems to be a "thread" type. It was soft when I picked it up from the wet ground but rapidly dried hard and brittle.
Again it was boiled for an hour, allowed to steep overnight and the vegetable matter strained out.
I also put some DMC cotton thread in with the wool. It has taken the dye much less strongly and is a pale ivory colour. I plan to leave them in the light to see if they darken like the last lot.
Now just need to find a lichen that gives a different colour.