hi Gavin,

This is something we get a lot of questions about. We do 3 body fits - regular, slim fit and fully fitted and there are slight differences in the chest and waist measurements in each fit. Our regular fit is a more generous cut with more fabric around the waist. If you like your shirt a bit closer fitting, our slim fit is probably the right fit for you. Fully fitted is slightly slimmer still. The best thing to do would be to work from your collar size and see where your waist and chest measurements fit best on our shirt sizing charts to see which shirt styles would fit you best. I hope that helps! 

For a bit of help on measuring your existing shirts to see which T.M.Lewin body fit is best for you, watch our how to measure yourself for shirt size video.