Hi Polly,
The older Ferroli boilers with a pilot light can only be lit when the boiler has a demand for heating or hot water. The best way to light it is to run a hot tap, you should hear the fan speed up then press and hold in the white button on the left hand side, after around 20 seconds the pilot should light. Keep the button pressed for a further 30 seconds then release, the pilot should stay in and the main burner should light. You can now turn the hot tap off. There should be some instructions on the drop down panel if fitted.
Note if you dont hear the fan running it may be stuck, this is quite common on these boilers.
Ian, September 2008