It's nice down the shops when the staff recognise you and ask after your health, even if it's only:

how's your backside for plooks?

The news is that you will now be recognised when you visit a Tesco petrol station. But it will be done by face-scanning technology.

The point of the exercise is not to extend a welcome. It is to examine the coupon of queuing customers to determine age and gender and then target them with appropriate advertisements via a screen at the till.

This could lead to confusion. A young bloke is getting the hard sell to buy hair gel when an old geezer hoves into view and suddenly the advert changes to Steradent and incontinence pads.

An organisation called Big Brother Watch (surely an oxymoron; who watches Big Brother these days?) is concerned that this scanning is an invasion of privacy.

With facial recognition technology getting more advanced, you may be queuing to pay for groceries and a camera is "literally scanning who you are".

Tesco insist no images or personal information about the individual are recorded or stored. Which seems a bit pointless and a waste of technology.

Why not have each customer identified via retinal screening as they enter the store so that a full personal service can be provided?

The first part of the process will be the credit check with the offer, should it be necessary, of an instant Tesco bank loan. Each trolley will be fitted with cameras and sensors which can carry out a full body scan. The trolley will be programmed to take big fat people automatically to the aisles with all the biscuits, crisps and ginger.

There will be interactive warnings such as: "Do you realise you have just walked past the freezer with the chocolate chip ice cream?"

There will, of course, be a facility to switch to the healthy option. After a full scan, with BMI and body fat measurement, the customer may be booked in for an appointment with the Tesco GP whose surgery is located between the Tesco optician and the Tesco lawyer.

On a fashion note, screens will have a photoshop facility showing how customers might look after a makeover from the F&F clothing range.

The ID screening system will, of course, welcome you by name.

But won't ask how your backside is for plooks because it already knows.