The stereotype is a common UK one and has nothing to do with the Ipswich murders.

I'd question whether there is a widespread stereotype about lorry-drivers as murderers.   If anything the stereotype of lorry-drivers is pretty favourable - in contrast to that for white-van drivers, and even they aren't thought of as murderers.
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Here's Reg Meuross on YouTube singing his song about his father, Good With His Hands. Hell of a song too.

Worth a million Jonathan Rosses and Russell Brands...