In a post on Instagram, the agency wrote: 'Did you know MI5 regularly receives letters from children across the UK who are interested in our work? 'Here's a glimpse of some of the letters we recently received, which brought smiles to our faces. In once comical letter, one ten-year-old child was seen asking the agency: 'Do you currently have a job for a ten-year-old? In their application they wrote: 'Dear MI5, I am writing to tell you that I would like to be a spy. 'I have been called a good spy and I think that I could be like a back-up person, spying on people but then not really.'