There was a rash of scares reported in the press during 1909.
This has been documented by:
Alfred M. Gollin, ‘England Is No Longer an Island: The Phantom Airship Scare of 1909’, Albion: A Quarterly Journal Concerned with British Studies, Vol. 13, No. 1 (Spring, 1981), pp. 43-57 [Jstor]
David Clarke in an article ‘Scareships over Britain – The Airship Wave of 1909’, Fortean Studies 6 (1999), pp.39-63
Nigel Watson (1980) Airships and Invaders: Background to a Social Panic
Brett Holman (2009) in his blog on Airminded.