something in common, because for the first time, they're all made of plastic, not paper. plastic, or polymer notes, last longer. so will we need so many of them? people ask that all the time. i think making polymer is more challenging, and it's different to paper because it lasts two and a half times. but actually, making cash more efficient is also an important part of keeping cash alive. these old paper £50 notes won't survive. you can't use them in shops from october next year. its replacement, featuring wartime code—breaker alan turing, is packed with security features, just like the place where it's being made. kevin peachey, bbc news. sir dermot turing, alan turing's nephew is with me now. good morning to you. good morning. how roud good morning to you. good morning. how proud are _ good morning to you. good morning. how proud are you — good morning to you. good morning. how proud are you that _ good morning to you. good morning. how proud are you that your - good morning to you. good morning. how proud are you that your uncle i good morning to you. good morning. how proud are you that your uncle is| how proud are you that your uncle is on the £50 note?— on the £50 note? well, i think that -auttin on the £50 note? well, i think that putting him — on the £50 note? well, i think that putting him on _ on the £50 note? well, i think that putting him on top _ on the £50 note? well, i think that putting him on top £50 _ on the £50 note? well, i think that putting him on top £50 note - on the £50 note? well, i think that putting him on top £50 note is i on the £50 note? well, i think that putting him on top £50 note is an l putting him on top £50 note is an astonishing thing. obviously, you