One of my main concerns about the first Secret Control was that we didn't want it to be so much of a secret that the riders would miss it. Otherwise the whole exercise would have been pointless. I had count-down signs at 33km, 29km, 6km, 4km and 2km away alerting riders to the approaching control, so we shouldn't have been too much of a surprise to them.
http://www.delphcyclist.info/pic/LEL_pic3.jpgThe interesting bit was that our actual control was off the route! Instead, we used that as our volunteers base and for toilets, first aid and mechanical support, and used the local cricket club (which was on the route) as our "stamping ground". We made sure that you could hardly miss it!
http://www.delphcyclist.info/pic/LEL_pic1.jpgAnd just in case you did miss it, just a bit further down the lane we had another sign telling riders to u-turn if they hadn't seen the secret.
http://www.delphcyclist.info/pic/LEL_pic2.jpgI was just a bit concerned about riders approaching us in the dark, suddenly finding a bunch of ne'e'r-do-wells diverting them into a field for some evil purpose.
Our location also gave us a perfect spot to monitor for any camper vans on the road. I don't know what the official supporters' route was, but it was very definitely not on that road between Helmsley and us. It was so twisty and narrow that when I drove my van on it the day before to put out the signs, I was realy grateful not to have to pass any cyclists.
It was bad enough that the local farming community were moving some extremely large and alarming looking agricultural machinery which all but filled our narrow lane but we had brilliant cooperation from them and no cyclists were harmed.