Just back from my local Tesco in Bangor (NI) and noticed that you can get double Clubcard points when you shop on a Monday, Tuesday or Wednesday. I cannot see this featured on the Tesco website or if it exists at all stores.
This seems to be no time limit on it.
Just spotted that this offer expires on 18th March 2007 and is limited to 3 tranactions per day. Strange that it finishes on a Sunday !!!