Canned bird song at the South Downs National Park headquarters ruffles feathers

But to neighbours to was ‘like Chinese water torture’ especially when it was discovered that the song was coming not from real birds but from a soundtrack which had been accidentally set to run constantly.

Charles Hanrahan, the West End theatre production costumier who has his studios in nearby Capron House, said: “It’s been hell. It’s been going on for three weeks and not just all day but all night as well when I thought birds stopped singing. We have been working to a deadline and have been here until 10pm for many nights lately and the sound has driven us crazy, making it hard to work.”

A spokesman for the park authority said the setting on the sound track had been accidentally knocked and had been running constantly. But as park staff were not at the headquarters in the evening they had not known.

“Swifts are gregarious birds so we have been playing a recording of their call to attract a breeding pair to a nest box in the South Downs Centre.

“If we’re successful then we hope to webcast footage of their chicks as they hatch and grow. “There was an accidental change in the settings and we apologise if this has caused any disturbance to our neighbours we have now adjusted the volume and time settings to fix this.

We are also eagerly watching our four house martin boxes, three for house sparrows and one for either wagtail or robin although we will not be able to webcast footage from them.”