I am frequently appalled by the poor diction and presentation of announcements on BA flights, and sometimes simply don't know how anyone whose first language isn't British English can possibly understand them. Even the safety demonstration is often rushed or mumbled.

Cabin crew, and especially the younger ones, need to slow down a little and pronounce the words more carefully (just a few dropped consonants, such as you hear in Estuary English, can make an entire sentence unintelligible to a non-native speaker). And those who produce the scripts need to cut out the flowery and superfluous language and simplify the message.