there is a great program in the UK called Thr Mcguire Program. check it out. they have videos on you tube, there are clips of a show called "school for stammerers" and a great one called "musharaf finds his voice ". he went on to do the Mcguire Program. also look into a singer clee Gareth gates. he was a pop idol contestant who froze when he tried to say his name but sung like an angel. there are a few types of people who stammer, thst I learned on the Mcguire course. overt and covert. overt would be like your colleague, who has an obvious stammer. you sound like a covert stammerer becuaar you hide it well (like by keeping quiet ". it's awful. I had so much to say but was too scared to say it. the course teaches self acceptance and has a lifetime support network. i highly recommend it. actually, after I completed the course I took a job sitting at a desk answering phones! I disclosed my stammer at the interview and that I had the tools to help beat it now and they shired me. they later said they were concerned abkut my speaxh but gave me a chance. let me know if you have any questions. pm or open chat is fine. good luck amd welcome to the stuttering club! ps, I had a colleague who stuttered too... we both never talked about our stutter to each other, but when we spoke we would stammer like crazy! after my course I told him about it. he was reluctant to join but eventually did it, after watching me phone for a taxi on a night out together.