A new camera overlooking the nesting site, in one of the towers, has been installed by the RSPB and the Sussex Ornithological Trust..

In the past, this has captured pictures of the imposing birds of prey with their eggs, and the arrival and growth of the chicks.

Adrian Thomas, of the RSPB, said the nesting box had been cleaned out before the peregrines arrived. “Apparently, they are not the cleanest of housekeepers,” he added.

“The pair are regularly on the cathedral, and making plenty of noise as they work themselves up to the breeding season.

“In birds it is all heavily hormone-regulated, so things don't happen until hormone levels reach critical points.”

The female was expected to start nest scraping – making a depression in the gravel – in the second half of March.

She started this on March 18 in 2003, March 26 in 2004, March 22 in 2005, and late March in 2006.

Egg-laying should progress quickly after that, with the fourth egg expected by April 1.

“It will be interesting to see if the unseasonably warm weather will advance the season at all,” Mr Thomas added.