1.5" wide shoes for front of twin-leading shoe brakes. Bonded friction material to prevent rivet damage. Sold in sets of four. Aftermarket.
Consider replacing the return springs AAU8243 when you do this job. Note that no Mini ever used these wide brake shoes on the rear, and it is a mistake to attempt to fit them in the rear. See GBS0701 for 1.25" wide rear sets.