Aloe inermis comes mainly from Yemen. It is clearly happy on The Rock!
Kew Gardens in London donated many aloes to the Gibraltar Botanical Garden, rather than growing them only in hothouse or adverse conditions, which the English environment would be for some of these warm and dry climate species. Gardeners need to bear in mind what plants can reasonably be expected to grow in the climate of their home gardens.
This photograph was taken in the Gibraltar Botanical Garden. Wherever you may visit, including the local botanical garden in your itinerary usually pays off. The one in Gibraltar was definitely worthwhile in 2006.