Using a cheese slicer, cut very thin slices of cheese horizontally from cheese block.
In a small bowl, stir together mayonnaise and mustard until combined.
Spread a layer of mayonnaise mixture onto 8 bread slices. Arrange 2 ham slices each on 4 bread slices. Place cheese slices over ham. Top with remaining bread slices, spread side down, to make 4 whole sandwiches.
Using a serrated bread knife in a gentle sawing motion, trim and discard crusts from each sandwich to create a 4½×2½-inch rectangle. Cut each sandwich into 3 (2½×1½-inch) rectangles. Serve immediately, or cover with damp paper towels, place in a covered container, and refrigerate up to 2 hours before serving.
Notes
*We used Colman’s Original English Mustard.
*We used Lincolnshire Poacher cheese, available at Whole Foods, and Colman’s Original English Mustard.
Recipe by TeaTime Magazine at https://teatimemagazine.com/ham-and-cheddar-tea-sandwiches-recipe/