Lots probably already know, or are too sharp to ever get caught out, but for anyone else and their relatives: apparently it started (or started getting reported) on Monday.
It's an automated call confirming your Tesco's order and the amount taken from your bank account and if you didn't order please press 1 to speak to our fraud team.
This one came from 07839097304 which when I googled it didn't link to anything.