Changes in temperature alter the viscosity of the pitch. The higher the temperature the lower the viscosity and the more readily the pitch flows. That natural variation has been confused in recent years with the installation of air conditioning in two lecture theatres either side of the foyer where the experiment sits. Professor Mainstone says the flow of cool air from the theatres has probably slowed it down. Now the burden of waiting is likely to be shared around the world live on the internet.
Physicists are very patient people.
They're prepared to wait a long time for results.