Sift the flour,
baking powder, and salt into a large bowl. Use a
pastry blender to cut in the butter until the
mixture resembles fine crumbs.
Add the egg,
beating until just blended. Stir in the sugar,
cherries, and vanilla to form a soft dough. Turn
the dough out onto a lightly floured surface and
knead until smooth.
Form the dough into a long log
2 inches (5 cm) in diameter, wrap in plastic wrap,
and refrigerate for at least 30 minutes.
Preheat
the oven to 375°F/190°C/gas 5. Butter three
cookie sheets. Slice the dough 1/2 inch (1 cm)
thick and place 1 inch (2.5 cm) apart on the
prepared cookie sheets.
Bake, one sheet at a time,
for 8-10 minutes, or until just golden. Transfer
to racks to cool.