Lewis Carroll tells us that the Cheshire cat in Alice in Wonderland left nothing behind but his grin. There were no researchers following him, however, avidly collecting the dust beneath the wall he had been sitting on, and examining it for the presence of Fel d 1. Alice was puzzled by her ‘grin without a cat’, as puzzled no doubt as Chan-Yeung and coworkers on the remote island of Tristan da Cunha. This is one of the two papers in this issue looking at allergy to cats. The researchers investigated a small population of people known to have high rates of asthma (102 out of 282 islanders studied). In this cross-sectional population-based study they found subjects sensitized to cat allergen, with cats long gone, and little evidence of Fel d 1, at least in settled dust. They report that 20.1% of the islanders tested had a positive skin test to cat dander (12.8% of the group born at least a year after complete extermination of cats).