Even at the most solemn moment of a funeral service, with relatives of the deceased weeping quietly into handkerchiefs, rest assured that William will roll up to add his special blessing. Rossini's WilliamTell, that is – set at "outdoor" on someone's mobile. Nothing is more intrusive, impolite and plain embarrassing. But now, at last, for those of us brassed off with monotone Mozart and high-pitched Handel, salvation dawns – a signal jammer that blocks all calls round a building.

Developed by Israeli electronic-warfare experts, the device is being trialled by four churches in Monterrey, Mexico. "Before we had the system, it was very uncomfortable hearing calls during the celebration of mass. But now it's 95 per cent quiet," said Bulmaro Carranza, from the Sacred Heart Church. "We are getting calls from all over the world to see how it can be installed in other churches – but only when the services are over!"