If you do this you also need to be sure to pay with cash, or other anonymous cards, because they’ll also link your payment details if I recall correctly (perhaps not this brand, but most others will).

Yes, retailers can and do link/track purchases against card numbers. But this is true regardless of whether you're a member of a loyalty scheme or not.

Also, if you use Apple Pay / Android Pay, a device account number (DAN) is generated that is different from your physical card number. I'm not sure whether retailers get a name from such a transaction, but I suspect they just get the card number?

Nope, it can be linked back using https://developer.visa.com/capabilities/visa-par-inquiry

It’s even more annoying than that, the various Card companies sell your data too! It’s a hot mess.

For a 1% return? Hardly worth it.

As for the app, I don't want my phone polluted with even more crap. If I had a corporate loyalty app for every shop I wanted to go in, I'd have a hundred apps, a hundred data collection problems and a flat battery. Instead I have one called Apple Pay which works everywhere..

I'd argue 1% isn't so bad in itself, but it works out to far more than that using the various bonuses and vouchers etc.

Personally I find the Sainsbury's scheme (Nectar) better overall, however. All the "vouchers" that multiply your points are applied automatically through the app, rather than having to goof around with scanning barcodes as in the Tesco app.

I haven't worked out my exact spend at Sainsbury's this year, but it was probably less than £1000. From that I had enough nectar points to buy £100 worth of wines in a recent promotion, and I still have plenty left over... (points, that is. Most of the wine is gone, haha)

For what it's worth, you can install the Clubcard app, add your Clubcard to Apple Pay from within the app, then uninstall it and the card will stay in Apple Pay.