Apparently the concept of a 1-click unsubscribe mechanism is completely lost on those responsible for the Tesco website. Here are the unsubscribe steps required to stop e-mails from the Tesco online store:

Once you have logged in to www.tesco.ie follow these 4 steps to unsubscribe.

1. Select the "log out/my details" tab from the top menu.
2. Go to the "Update My Details" section and click on "click here to update your details.
3. Scroll down to the "Data Protection" section and click on the link "click here to receive information about Tesco products and services".
4. Check the box after the sentence "I do NOT want to receive offers and information about Tesco products and/or services." Press Submit.

It may take up to five working days to unsubscribe.

Sometimes I worry that I'm pretty thick and that one day I won't be able to find employment. Then I realise that some company is still paying the people who build these systems a wage, despite the utter complete mess they make of it - and I feel a bit more confident that I won't be jobless. I mean someone who built this system must have looked at the above and thought "yea - this is terrible".