I had the same issue when I first tried them and mentioned it to Ed who advised me to start with a less wet brush and add water slowly and gradually. It worked a treat and resulted in beautiful lather and near perfect shaves. Oh and that with very little soap loaded.My review of Edward's older formula is here: https://www.atgshaving.com/threads/review-london-oatcake-soap.12551/
His new formula is far better which I summarized with the following:
"The slickness is really improved with this new formula from the last batch. Post-shave is just as great as before which I'm glad.
However, the lather just looks different from other soaps, something that I just can't explain. I'd get the lather to a dense and glossy point, and then during the first pass the lather in the bowl would lose the glossy sheen and turn matte. Maybe it's my East-Anglia hard water.
The only way I could get a relatively stable lather was to load the brush really heavily (far beyond what I would use comfortably) which would widen the water content sweet-spot enough to help stabilize it.
Overall, I got really good shaves from this new formula. It's a bold step in the right direction. "