Salem,
La hawla wala quwat ila billah!!!!!
I know how annoying this picture is for all Muslims, but I think the finger is being pointed at the customs officers in the UK who the artist sees as being inefficient in detecting possible threats. I'm not justifying this portayal of Muslims as "terrorists", it's unforgivable!!!!! It's all part of the general ignorance of the majority of people who don't know the real Islam as a religion of tolerance and peace.
Go ahead and file your complaint, and explain just how offensive this is for Muslims, and that, as one of the staff in this organisation, you expect respect from all. Sometimes, people are so insenstive that they don't realise that something they find amusing is totally off-limits for others.
Hasbi Allah wa na3mel alwakeel.