Here is a brief race report from Richard Slack on what I imagine is a beautiful run:
10 miles round Derwent Water clockwise from Keswick. Route goes down the Borrowdale Road to Grange, over the bridge and then up the hill, hill, hill (about 700 foot ascent) to the top of Catbellls road. Drop down (hurray) after the cattle grid towards Portinscale finish. Tough but great and just over 8 minute miles. Sun shone and stunning views all the way. Beats Denton Bank in the winter!