Simon: I love your avatar! I even have a Wallace & Gromit shave kit. Anyway, the flat part on the top of the baseplate of my New Improved Tuckaway measures about 13mm compared to 15mm on my English NI Richwood. I think Cornishman's observation is one of the most interesting things I've read about on this forum for months. I can't wait to compare my two NI heads to see which one I like better.