For the uninitiated, the "Richmond Formula" is a formula used by the Lib Dems (and now copied by other parties) based on a system pioneered by Richmond Lib Dems in the 1980's which saw them take raw canvassing data from knocking on doors, and using the formula to extrapolate a potential result.
At the time that Richmond lib Dems developed the formula, they worked out which seats were "in the bag" from applying the formula, and then went to help in more marginal areas.
So what would Richmond Lib Dems have done with the 12% lead that Nick Clegg has over Chris Huhne (according to a Sky News poll) ? My guess is they would assume there is a clear winner.
I have to say, when i have run local elections I have assumed a 12% margin to be fairly accurate.