As update - I actually ran around the Clwydians 3 days after the break and continued to do so throughout the 4 weeks whilst in cast - mostly whilst wearing sling. This included a Bob Graham reccie and also The Hebden race.
Ran pretty decent with little discomfort. At no point did I fall, which may have hurt a bit. The only major ache was around the back of the neck from the sling, but I went back to the hospital and they gave me a better one and at no point seemed bothered that I was running with it.
Cast off now - happy days