The reason they mention that is because of DFT's requirements for a 5-year background security check before you are issued with an airside pass. It's, however, a short cut taken by all the handling agents since they don't know how to ask for references in foreign countries (in some of these, employers would be reluctant to release such information anyway). My advice is to apply anyway since this requirement is illegal with respect to EU non-discrimination rules.
After all, most UK airlines have non-British pilots and Cabin Crew, and they have unescorted airside passes!
Cheers
