Info for the 2008 Yoredale 100 is at www.wizzer5.co.uk .
Info for the Round Rotherham event can be found thro the Rotherham Harriers website
You could even join the LDWA ! and save the fee on the premium charged to non-members to enter the hundred -if there's any places left for them.
The events you are looking for are " Challenge Events " in the calendar ,filter out the social walks .Those left will state "walkers only " if they don't want runners or "no runners " or even worse "no dogs , no runners " in that order !