We, the undersigned, recognise that Silbury Hill is a world monument of inestimable importance. We are dismayed by the delay in rectifying the ongoing collapses that began in May 2000.

We are concerned that further catastrophic collapses may occur, despite your assurances, and we doubt that definitive expert opinion to allay our fears can be supplied.

We therefore now call upon you to provide the international public with the full technical basis for your assurances or, if no such assurances can be obtained, to announce an urgent timetable for securing the monument's stability.