I wrote to Tesco following my post on Tesco's so-called accessibility.
To recap, you cannot use Visa Electron debit cards, which many basic bank account holders have, on tesco.com (you can use them in store, which makes the anomaly even more annoying). This means that many housebound, poorer people are blocked from online shopping.
Not a very useful response from them, no actual answer to my question:
Thank you for your email.
I am sorry to learn that you cannot purchase groceries using your Visa Electron card on our home shopping website. I sincerely apologise for the inconvenience caused due to this.
I have checked and can confirm that when you order online you can use debit or credit cards, but we're unable to accept cash or cheques.
All of our online stores, Tesco Direct and our online Photo Centre accept Visa, Mastercard, American Express, Switch/Maestro, and Delta.
Our Grocery store also accepts Solo cards. But if you have an Electron card, please check with your issuing bank, as they can upgrade your card to allow you to shop online with us.
I hope this has made things clearer for you. Please accept my apologies for any disappointment caused on this occasion. Thank you for showing an interest in Tesco.com.
If you have any further queries please do not hesitate to contact us at email@example.com quoting TES3349367X.