Anybody want to hazard a guess as to how long it might take me to cycle over the Wrynose and Hardknott Passes?

Googlemaps informs me that it's 12.3 miles from Skelwith Bridge to Boot... is two hours enough for that journey (not racing, just pushing along nicely)? Even with the climbs, surely average of 6mph can't be too ambitious?

I'm no dedicated cyclist, but have been known to get on a bike and do 50+ miles with not much prior thought. Obviously i'd likely be pushing up sections of the passes i'd have thought.