I don't know if this is a glitch in their system, or if Tesco intend to sell them as the same price as the standard Polyurethane Covers.
However the leather cases should retail for £69 on Apple, and they usually don't allow other retailers to sell their products much cheaper.
I have ordered a leather one myself for collection at my local store. All went thru okay.
(*edited sorry other poster is correct £59 at Apple)
Update 13:14 /26/03/2011 NOT EXPIRED