ROFLMAO AKiron.
There was a guy who used to live next to Heathrow airport, apparently he covered the chainlink fennce in his garden with foil to suck power out of their ATC radar and light his house. A tall story, but it shouldbe true even if it's not
I may get up to Menwith Hill to take pics etc, and I shall be bringing a foil wrapped pheasant or two in the hope they bump up the output.
But seriously, I don't believe a few dozen peaceniks with UFOkites and mylar balloons are going to cause much disruption, other than tears of hilarity down the COs cheeks.
Make that quarter of a million mylar balloons then you're in business!